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Journal articles on the topic 'D Orbital splitting'

Author: Grafiati

Published: 11 December 2022

Last updated: 26 January 2023

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YAO, YAO, YU-ZHONG ZHANG, HUNPYO LEE, et al. "ORBITAL SELECTIVE PHASE TRANSITION." Modern Physics Letters B 27, no. 20 (2013): 1330015. http://dx.doi.org/10.1142/s0217984913300159.

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In this paper, we review theoretical investigations on the origin of the orbital selective phase where localized and itinerant electrons coexist in the d shell at intermediate strength of the on-site Coulomb interactions between electrons. In particular, the effect of spatial fluctuations on the phase diagram of the two-orbital Hubbard model with unequal bandwidths is discussed. And different band dispersions in different orbitals as well as different magnetically ordered states in different orbitals which are responsible for orbital selective phase transitions are emphasized. This is due to the fact that these two mechanisms are independent of the Hund's rule coupling, and are completely distinct from other well-known mechanisms like orbitals of unequal bandwidths and orbitals with different degeneracies. Moreover, crystal field splitting is not required in these two recently proposed mechanisms.

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Kang-Wei, Zhou, and Zhao Sang-Bo. "On 'Zhao's d-orbital theory' for zero-field splitting." Journal of Physics C: Solid State Physics 20, no. 24 (1987): L583—L589. http://dx.doi.org/10.1088/0022-3719/20/24/002.

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He, Yuping, Catalin D. Spataru, Francois Léonard, et al. "Two-dimensional metal–organic frameworks with high thermoelectric efficiency through metal ion selection." Physical Chemistry Chemical Physics 19, no. 29 (2017): 19461–67. http://dx.doi.org/10.1039/c7cp03310a.

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Klahn, Emil Andreasen, Emil Damgaard-Møller, Lennard Krause, et al. "Quantifying magnetic anisotropy using X-ray and neutron diffraction." IUCrJ 8, no. 5 (2021): 833–41. http://dx.doi.org/10.1107/s2052252521008290.

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In this work, the magnetic anisotropy in two iso-structural distorted tetrahedral Co(II) complexes, CoX 2tmtu2 [X = Cl(1) and Br(2), tmtu = tetramethylthiourea] is investigated, using a combination of polarized neutron diffraction (PND), very low-temperature high-resolution synchrotron X-ray diffraction and CASSCF/NEVPT2 ab initio calculations. Here, it was found consistently among all methods that the compounds have an easy axis of magnetization pointing nearly along the bisector of the compression angle, with minute deviations between PND and theory. Importantly, this work represents the first derivation of the atomic susceptibility tensor based on powder PND for a single-molecule magnet and the comparison thereof with ab initio calculations and high-resolution X-ray diffraction. Theoretical ab initio ligand field theory (AILFT) analysis finds the d xy orbital to be stabilized relative to the d xz and d yz orbitals, thus providing the intuitive explanation for the presence of a negative zero-field splitting parameter, D, from coupling and thus mixing of d xy and d_{x^2 - y^2}. Experimental d-orbital populations support this interpretation, showing in addition that the metal–ligand covalency is larger for Br-ligated 2 than for Cl-ligated 1.

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Shang, Jing, Chun Li, Xiao Tang, et al. "Multiferroic decorated Fe2O3 monolayer predicted from first principles." Nanoscale 12, no. 27 (2020): 14847–52. http://dx.doi.org/10.1039/d0nr03391j.

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Li, Zhenyu, Linmin Zhao, Hui Chen, et al. "Crystal phase-selective synthesis of intermetallic palladium borides and their phase-regulated (electro)catalytic properties." Catalysis Science & Technology 12, no. 4 (2022): 1038–42. http://dx.doi.org/10.1039/d1cy02112e.

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Three Pd–B intermetallics, namely, Pd6B, Pd5B2 and Pd2B, are synthesized, and their catalytic activities toward electrochemical water splitting and Suzuki coupling reactions are strongly associated with the Pd(d)–B(s,p) orbital hybridization.

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Li, Yu-Qiong, Qian He, Jian-Hua Chen, and Cui-Hua Zhao. "Electronic and chemical structures of pyrite and arsenopyrite." Mineralogical Magazine 79, no. 7 (2015): 1779–89. http://dx.doi.org/10.1180/minmag.2015.079.7.05.

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AbstractThe first-principles plane-wave pseudopotential method is used to study the electronic and chemical structures of pyrite (FeS2) and arsenopyrite (FeAsS). The results indicate that an antibonding interaction occurs between Fe and As atoms in arsenopyrite. This interaction results in the Fe atom being repelled towards the S atom to stabilize antibonding orbitals, causing a larger S–Fe–S angle in arsenopyrite than in pyrite and a distortion in the arsenopyrite structure. In arsenopyrite, Fe–Fe distances are alternately long and short. The low spin density of the Fe d electrons supports this configuration in arsenopyrite. However, electron density calculations indicate that there is negligible electron density present between Fe atoms. This result indicates that cation-anion interactions are dominant in arsenopyrite. The pyrite Fe 3d orbital is split below the Fermi level, whereas the arsenopyrite Fe 3d orbital is not split, which can be attributed to the stronger interatomic bonding effects between Fe and S atoms in pyrite compared to arsenopyrite. It is found that the d-p orbital interactions between Fe and S atoms lead to bonding-antibonding splitting in both pyrite and arsenopyrite. However, the bonding effects between pyrite Fe and S atoms are stronger than in arsenopyrite. In arsenopyrite, the bonding interaction between the As 4p and Fe 3d orbitals is very weak, while the antibonding effect is very strong. The p-p orbital interaction is the dominant effect in As–S bonding. Frontier orbital calculations indicate that the Fermi levels of pyrite and arsenopyrite are notably close to each other, resulting in similar electrochemical activities. Orbital coefficient results show that the pyrite Fe 3d and S 3p orbitals are the active orbitals in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), respectively. In the case of arsenopyrite, Fe 3d orbitals are very active in both the HOMO and LUMO. Moreover, the activity of the As 4p in the HOMO is greater than S 3p, whereas the opposite situation occurs in the LUMO. Based on these results, As atoms could be one of the active sites for the oxidation of arsenopyrite. In addition, separation of arsenopyrite and pyrite could be achieved by utilizing the difference in chemical reactivities of iron in the two minerals.

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Pavlík, Ivan, Josef Fiedler, Jaromír Vinklárek, and Martin Pavlišta. "Ligand Field Model and d-d Spectra of dN Metallocene Complexes." Collection of Czechoslovak Chemical Communications 66, no. 2 (2001): 228–54. http://dx.doi.org/10.1135/cccc20010228.

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Complete ligand field calculations, including spin-orbit coupling, have been carried out for bent d1 metallocene complexes, [M(Cp)2Ln] (Cp = η5-cyclopentadienyl, n = 1 or 2), in C2v symmetry. Using the strong-field coupling formalism (with exclusion of spin-orbit coupling) the full energy matrices for d2, d3, and d4 bent metallocenes were constructed in terms of four ligand field splitting parameters and two Racah interelectronic repulsion parameters (only d2 energy matrices are presented here). The bonding in the bent d1 C2v M(Cp)2 fragment was analyzed from the point of view of the ligand field model. The experimental d-d transition energies of two d1 metallocene dichlorides, vanadocene and niobocene dichlorides, have been assigned, the values of four one-electron ligand field splitting parameters determined and the effect of spin-orbit coupling estimated. The ground state of both d1 metallocene dichlorides has shown to be 2A(111), the d-orbital energy order being 1a1 < b1 < b2 < 2a1 < a2. Finally, the prediction of d-d spectra for d2, d3, and d4 bent metallocene complexes is presented.

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Suzuki, Atsushi, and Takeo Oku. "Electronic Structures, Spectroscopic Properties, and Thermodynamic Characterization of Alkali Metal and Transition Metal Incorporated Perovskite Crystals by First-Principles Calculation." Materials Proceedings 4, no. 1 (2020): 79. http://dx.doi.org/10.3390/iocn2020-07942.

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The influence of alkali metals (Na, K) or transition metals (Co, Cr, Cu, and Y) incorporated into perovskite crystal on the electronic structures, spectroscopic, and magnetic properties, and thermodynamic properties was investigated by first-principles calculation. Incorporation of Na or K into the perovskite crystal generated 3s, 3p, 4s, and 4p orbitals of Na or K above the conduction band, which promoted the charge transfer from alkali metal to the conduction band, accelerating the electron diffusion related to the photovoltaic properties. For the Cr, Cu, and Y-incorporated perovskite crystals, the electron density distribution of d-p hybrid orbital on the transition metal and iodine halogen ligand were delocalized at frontier orbital. The electronic correlation worked in between the localized spin on 3d orbital of the metal, and the itinerant carriers on the 5p orbital of the iodine halogen ligand and the 6p orbital of the lead atom in the perovskite crystal. The vibration behavior of the Raman and infrared spectra were associated with change of polarization and slight distortion near the coordination structure. The considerable splitting of chemical shift of 127I-NMR and 207Pb-NMR in the magnetic field was caused by crystal field splitting with the Jahn-Teller effect with nearest-neighbor nuclear quadrupole interaction based on the charge distribution. Decrease of the Gibbs free energy and entropy indicated the thermodynamic stabilization without scattering carrier diffusion as phonon effectiveness. The decrease of the entropy was based on a slight change of stretching vibration mode of Pb–I bond with vending mode of N–H and C–H bonds in the infrared and Raman spectra. The minor addition of alkali metal or transition metal into the perovskite crystal would improve the photovoltaic properties, open voltage related to band gap, and short-circuit current density based on the carrier diffusion with phonon effectiveness.

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Wu, Liang, Wenzhe Zhou, Dehe Zhang, and Fangping Ouyang. "Theoretical study of spin-orbit coupling in Janus monolayer MA₂Z₄." Journal of Physics: Conference Series 2263, no. 1 (2022): 012014. http://dx.doi.org/10.1088/1742-6596/2263/1/012014.

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Abstract In this paper, based on first-principles calculations, we investigate the energy valley and spin-orbit coupling properties of Janus monolayer MA2Z4. The stability of different structures is illustrated. Due to the breaking of mirror symmetry, Rashba splitting occurs at the Γ point in the band structures of Janus monolayers WSiGeN4 and WSi2(NP)2. The relationship between Rashba spin-orbit coupling strength and potential energy gradient and d-orbital composition is explored. Janus monolayer WSi2(NP)2 has stronger Rashba effect than WSiGeN4 due to the strong asymmetry of the d orbital of W atom. These results help to promote the application of two-dimensional materials in spintronics and valleytronics.

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Li, Hai-Long, Liang Bian, Fa-Qin Dong, Wei-Min Li, Hao Zou, and Mian-Xin Song. "Effects of halogen substituted on the Mn-O electron transfer of NiMn2O4." International Journal of Modern Physics B 33, no. 10 (2019): 1950090. http://dx.doi.org/10.1142/s0217979219500905.

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To observe the effect of halogen-substitution on the Mn-O electron transfer of NiMn2O4, we calculated Mn-mixed-valence configuration (charge-disproportionation) and oxygen vacancy by the density functional theory (DFT). The results indicate that the halogen-p5 state induces the O-2p orbital splitting to create an oxygen vacancy in the VB (valence band: about −5 eV). The oxygen vacancy can capture an electron from Mn[Formula: see text]-3d5 orbital that makes the Mn[Formula: see text]-3d5 change to Mn[Formula: see text]-3d4 states (Mn-charge disproportionate), and providing many effective-hole (40.14 [Formula: see text] 96.72 × 10[Formula: see text] kg). The halogen-p5-O-2p4 hybrid orbitals enhance the O-2p4-Mn-3d5 p-d hybrid orbital (about 19.18 electron). That increases the surface potential in Mn-O octahedron (for Cl-substituted: about 60 meV), the corresponding electron–electron interactions change from complex t[Formula: see text] (O-2p4-Mn[Formula: see text]-3d[Formula: see text] to complete [Formula: see text] (O-2p4-Mn[Formula: see text]-3d[Formula: see text]-e[Formula: see text](O-2p4-halogen-p5) orbital. This study effectively analyzes the microscopic changes of the electron transfer caused by the small amount of doping, provides a theoretical basis for the design of NMO-based semiconductor material.

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Rachuru, Sanjeev, V. Jagannadham, and R. Veda Vrathc. "A simple rule of thumb for the explanation of d-orbital splitting in complexes." Educación Química 31, no. 4 (2020): 35. http://dx.doi.org/10.22201/fq.18708404e.2020.4.71913.

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<br /><table class="t1" cellspacing="0" cellpadding="0"><tbody><tr><td class="td1" valign="top"><p class="p2"><span class="s1"> </span>En las aulas de química a nivel preuniversitario y de ingeniería (disciplina no química) de primer año en universidades de la India, la división de los niveles de energía de los orbitales d en complejos es un concepto importante que debe aprenderse, pero no se explica explícitamente en los libros estándar usados. En los libros estándar como ‘Química inorgánica concisa’ de J .D. Lee y ‘Química inorgánica teórica’ de Marion Clyde Jr. Day y Joel Selbin, han explicado la división de los orbitales d en octaédricos, tetraédricos, planos cuadrados, etc. ., complejos muy bien. Lo mismo ocurre con el último libro de texto de química preuniversitario NCERT (Volumen I) escrito para la audiencia india. La razón por la que los niveles de energía de ciertos orbitales d están por encima del baricentro y por qué algunos están por debajo del baricentro, sin embargo, no se explica en ninguno de los libros (incluidos los últimos libros). Esta breve comunicación describe una simple regla empírica que permite explicar este fenómeno a los estudiantes. Además, se traza un gráfico importante en los libros estándar, pero no se explica la tendencia de la curva. Esta sencilla regla también es útil para explicar este gráfico y el fenómeno químico representado.<span class="Apple-converted-space"> </span></p></td></tr></tbody></table>

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Sheu, H. S., J. C. Wu, Y. Wang, and R. B. English. "Charge density studies in NH4[Ti(C2O4)2].2H2O crystals at two wavelengths." Acta Crystallographica Section B Structural Science 52, no. 3 (1996): 458–64. http://dx.doi.org/10.1107/s0108768195012900.

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The crystal structure of ammonium bis-μ-oxalatotitanate(III) dihydrate, NH4[Ti(C2O4)2].2H2O, is reinvestigated by careful single-crystal X-ray diffraction using Mo Kα (room temperature and 130 K) and Ag Kα radiation (room temperature). It crystallizes in noncentrosymmetric hexagonal space group P6422, with cell parameters a = 8.947 (2), c = 10.898 (1) Å, Z = 3, F(000) = 423, Mr = 278.1, Dx = 1.833, R = 0.035, wR = 0.030 for 2296 observed reflections with I ≥ 2σ(I), on Ag Kα data. Accurate data measurement was applied using two wavelengths (0.7107 Å for Mo Kα and 0.5609 Å for Ag Kα in order to study the charge density distribution and also to investigate the wavelength effect in such investigations. A total of 22650 and 20298 reflections were measured using Mo Kα radiation at room temperature and 130 K, respectively, and 18361 reflections using Ag Kα radiation. The Ti atom is coordinated by four oxalate dianions with coordination number 8 in an approximate symmetry of D 4 geometry. Each oxalato ligand is bridged between two Ti atoms and forms an infinite polymeric spiral column along the c axis. The deformation density maps, Δρ, obtained from all three data sets are consistent and agree well. Although the formal charge of Ti in this complex is 3+, with only one electron on the 3d orbitals expected, the net atomic charge on Ti from this study is, ~2+. Charge asphericity around the Ti atom caused by the splitting of 3d orbitals is clearly observed in the deformation density. The d-orbital populations are evaluated from multipole refinement. The expected d 1 electron is mainly located in the dZ2 orbital.

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Vogler, Conny, and Wolfgang Kaim. "Einkernige Bis(triphenylphospin)kupfer(I)-Komplexe der Bidiazine / Mononuclear Bis(triphenylphosphine)copper(I) Complexes of the Bidiazines." Zeitschrift für Naturforschung B 47, no. 8 (1992): 1057–62. http://dx.doi.org/10.1515/znb-1992-0801.

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The cationic d10 metal complexes [(bdz)Cu(PPh3)2+]+ of the π accepting bidiazine (bdz) chelate ligands 3,3′-bipyridazine, 2,2′-bipyrazine, 2,2′- and 4,4′-bipyrimidine were synthesized and compared with the analogous complex of 2,2′-bipyridine. The long wavelength metal-to-ligand charge transfer (MLCT) absorption maxima and the reduction potentials indicate relatively little π* orbital stabilization by +Cu(PPh3)2. The particular d orbital splitting in a tetrahedral ligand field results in an additional contribution from △t to the energy difference between the first and second MLCT band. Only the most easily reduced complexes of 4,4′-bipyrimidine and 2,2′-bipyrazine yield neutral radical complexes (“Cu(0)”) which were characterized by ESR spectroscopy.

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Dhawan, Rakshanda, Padmanabhan Balasubramanian, and Tashi Nautiyal. "Structural, electronic and magnetic properties of weakly correlated metal Sr₂CrTiO₆: a first principles study." Journal of Physics: Condensed Matter 34, no. 5 (2021): 055501. http://dx.doi.org/10.1088/1361-648x/ac334f.

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Abstract Structural, electronic and magnetic behaviour of a less-explored material Sr2CrTiO6 has been investigated using ab initio calculations with generalized gradient approximation (GGA) and GGA + U methods, where U is the Hubbard parameter. For each of the three possible Cr/Ti cationic arrangements in the unit cell, considered in this work, the non-magnetic band structure shows distinct traits with significant flat-band regions leading to large t 2g density of states around the Fermi energy. The Cr4+ ion in Sr2CrTiO6, which is a d 2 system, shows a reverse splitting of the t 2g orbitals. The calculated hopping matrix contains non-zero off-diagonal elements between the d xz and d yz orbitals, while the d xy orbitals remain largely unmixed. A minimal tight binding model successfully reproduces the six t 2g bands around the Fermi energy. The Fermi surface shows a two-dimensional nesting feature for the layered arrangement of Cr and Ti atoms. Fixed spin moment studies suggest that the magnetism in this compound cannot be explained by Stoner’s criterion of an itinerant band ferromagnet. In the absence of Hubbard U term, the ground state is a half-metallic ferromagnet. Calculations for the anti-ferromagnetic spin arrangement show re-arrangement of orbital character resulting in (a) narrow d xz /d yz bands and sharp peaks in the density of states at the Fermi energy and (b) highly dispersive d xy bands with a broader density of states around the Fermi energy. The metallicity persists even with increasing U for both the spin arrangements, thus suggesting that Sr2CrTiO6 belongs to the class of weakly correlated metals, while the shifting of O 2p states towards the Fermi energy with U indicates a negative charge-transfer character in Sr2CrTiO6.

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Małecki, J. G., A. Świtlicka, T. Groń, and M. Bałanda. "Correlation between crystal symmetry and the splitting of d orbital in the thiocyanate nickel(II) complexes." Polyhedron 29, no. 17 (2010): 3198–206. http://dx.doi.org/10.1016/j.poly.2010.08.030.

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Börgel, Jonas, Michael G. Campbell, and Tobias Ritter. "Transition Metal d-Orbital Splitting Diagrams: An Updated Educational Resource for Square Planar Transition Metal Complexes." Journal of Chemical Education 93, no. 1 (2015): 118–21. http://dx.doi.org/10.1021/acs.jchemed.5b00542.

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Fujisawa, Jun-ichi, та Kazutaka Hirakawa. "Mechanisms of large red-shift and intensity enhancement of absorption bands by π-bond breaking in a benzoporphyrin sensitizer for photodynamic therapy". Journal of Porphyrins and Phthalocyanines 18, № 06 (2014): 513–18. http://dx.doi.org/10.1142/s1088424614500278.

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A free-base monobenzoporphyrin photosensitizer called verteporfin for photodynamic therapy (PDT) has a benzopyrrole ring with a partial π-bond breaking. The π-bond breaking significantly red-shifts the absorption band (so-called Qy-band) to 688 nm and enhances the absorption intensity. In this paper, we theoretically study the mechanisms of the red-shift and intensity enhancement in verteporfin. Density functional analysis at the B3LYP-6-31G(d,p) level of theory reveals that the π-bond breaking increases the energies of the highest occupied molecular orbital (HOMO) and second lowest unoccupied molecular orbital (LUMO+1) by 0.28 and 0.11 eV, respectively, and decreases the energy of the lowest unoccupied molecular orbital (LUMO) by 0.08 eV, in contrast to the unmoving second lowest occupied molecular orbital (HOMO-1). In the consequence of the higher energy shift of the HOMO and lower energy shift of the LUMO, the HOMO–LUMO gap is significantly narrowed. Therefore, the absorption red-shift in verteporfin is attributed to the HOMO–LUMO gap narrowing. On the other hand, the molecular-orbital shifts split the four electronically excited states, (HOMO, LUMO), (HOMO, LUMO+1), (HOMO-1, LUMO), and (HOMO-1, LUMO+1). The splitting weakens the configuration interactions between the excited states, which enhances the transition probability of the Qy-band.

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Pike, Nicholas A., Ruth Pachter, Alan D. Martinez, and Gary Cook. "Computational analysis of the optical response of ZnSe with d-orbital defects." Journal of Physics: Condensed Matter 34, no. 20 (2022): 205402. http://dx.doi.org/10.1088/1361-648x/ac594a.

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Abstract The doping of wide band-gap semiconducting ZnSe by transition metal (TM) atoms finds applications from mid-infrared lasing, sensing, photoelectrochemical cells, to nonlinear optics. Yet understanding the response of these materials at the atomic and electronic level is lacking, particularly in comparing a range of TM dopants, which were studied primarily by phenomenological crystal-field theory. In this work, to investigate bulk ZnSe singly doped with first-row TM atoms, specifically Ti through Cu, we applied a first-principles approach and crystal-field theory to explain the origin of the infrared absorption. We show that the use of an appropriate exchange–correlation functional and a Hubbard U correction to account for electron correlation improved the determination of the electronic transitions in these systems. We outline an approach for the calculation of the crystal-field splitting from first-principles and find it useful in providing a measure of dopant effects, also in qualitative comparison to our experimental characterization for ZnSe doped with Fe, Cr, and Ni. Our calculated absorption spectra indicate absorption signatures in the mid-infrared range, while the absorption in the visible portion of the spectrum is attributed to the ZnSe host. Our calculations will potentially motivate further experimental exploration of TM-doped ZnSe. Finally, the methods used here provide a route towards computational high-throughput screening of TM dopants in III–V materials through a combination of the electronic band structure and crystal-field theory.

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Lin, Yifeng, Changcheng Zhang, Lixiu Guan, Zhipeng Sun, and Junguang Tao. "The Magnetic Proximity Effect Induced Large Valley Splitting in 2D InSe/FeI2 Heterostructures." Nanomaterials 10, no. 9 (2020): 1642. http://dx.doi.org/10.3390/nano10091642.

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The manipulation of valley splitting has potential applications in valleytronics, which lacks in pristine two-dimensional (2D) InSe. Here, we demonstrate that valley physics in InSe can be activated via the magnetic proximity effect exerted by ferromagnetic FeI2 substrate with spin-orbit coupling. The valley splitting energy can reach 48 meV, corresponding to a magnetic exchange field of ~800 T. The system also presents magnetic anisotropy behavior with its easy magnetization axis tunable from in-plane to out-of-plane by the stacking configurations and biaxial tensile strain. The d-orbital-resolved magnetic anisotropic energy contributions indicate that the tensile strain effect arises from the increase of hybridization between minority Fe dxy and dx2−y2 states. Our results reveal that the magnetic proximity effect is an effective approach to stimulate the valley properties in InSe to extend its spintronic applications, which is expected to be feasible in other group-III monochalcogenides.

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Zhang, Zhi Hong, Shao Yi Wu, Xue Feng Wang, and Yue Xia Hu. "Studies of the Spin Hamiltonian Parameters for NiX₂ and CdX₂:Ni²⁺ (X=Cl, Br)." Defect and Diffusion Forum 282 (January 2009): 25–30. http://dx.doi.org/10.4028/www.scientific.net/ddf.282.25.

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The spin Hamiltonian parameters (zero-field splitting D and the g factors) for NiX2 and CdX2:Ni2+ (X=Cl, Br) are quantitatively investigated from the perturbation formulas of these parameters for a 3d8 ion in trigonally distorted octahedra based on the cluster approach. In the calculations, the trigonal field parameters  and ′ are determined from the superposition model and the local structures of Ni2+ in the halides. The theoretical g factors show reasonable agreement with the observed values, and the experimental D for CdX2:Ni2+ are also interpreted by considering suitable lattice distortions (angular decreases) in the impurity-ligand bond angles related to the C3 axis due to the size mismatching substitution. The contributions from the ligand orbital and spin-orbit coupling interactions are important and should be taken into account.

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Rodríguez, Fernando. "Unveiling the Local Structure of Cu2+ Ions from d-Orbital Splitting. Application to K2ZnF4:Cu2+ and KZnF3:Cu2+." Inorganic Chemistry 56, no. 4 (2017): 2029–36. http://dx.doi.org/10.1021/acs.inorgchem.6b02677.

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Preece, Holly P., C. Simon Jeffery, and Christopher A. Tout. "Asteroseismology of tidally distorted sdB stars." Monthly Notices of the Royal Astronomical Society 489, no. 3 (2019): 3066–72. http://dx.doi.org/10.1093/mnras/stz2292.

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ABSTRACT Most subdwarf B stars are located in post-common envelope binaries. Many are in short-period systems subject to tidal influence, and many show pulsations useful for asteroseismic inference. In combination, one must quantify when and how tidal distortion affects the normal modes. We present a method for computing tidal distortion and associated frequency shifts. Validation is by application to polytropes and comparison with previous work. For typical sdB stars, a tidal distortion to the radius of between $0.2\,$ and $2\,$ per cent is generated for orbital periods of 0.1 d. Application to numerical helium core-burning stars identifies the period and mass-ratio domain where tidal frequency shifts become significant and quantifies those shifts in terms of binary properties and pulsation modes. Tidal shifts disrupt the symmetric form of rotationally split multiplets by introducing an asymmetric offset to modes. Tides do not affect the total spread of a rotationally split mode unless the stars are rotating sufficiently slowly that the rotational splitting is smaller than the tidal splitting.

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Silvotti, Roberto, Péter Németh, John H. Telting, et al. "Filling the gap between synchronized and non-synchronized sdBs in short-period sdBV+dM binaries with TESS: TIC 137608661, a new system with a well-defined rotational splitting." Monthly Notices of the Royal Astronomical Society 511, no. 2 (2022): 2201–17. http://dx.doi.org/10.1093/mnras/stac160.

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ABSTRACT TIC 137608661/TYC 4544-2658-1/FBS 0938+788 is a new sdBV+dM reflection-effect binary discovered by the TESS space mission with an orbital period of 7.21 h. In addition to the orbital frequency and its harmonics, the Fourier transform of TIC 137608661 shows many g-mode pulsation frequencies from the subdwarf B (sdB) star. The amplitude spectrum is particularly simple to interpret as we immediately see several rotational triplets of equally spaced frequencies. The central frequencies of these triplets are equally spaced in period with a mean period spacing of 270.12 s, corresponding to consecutive l = 1 modes. From the mean frequency spacing of 1.25 μHz we derive a rotation period of 4.6 d in the deep layers of the sdB star, significantly longer than the orbital period. Among the handful of sdB+dM binaries for which the sdB rotation was measured through asteroseismology, TIC 137608661 is the non-synchronized system with both the shortest orbital period and the shortest core rotation period. Only NY Vir has a shorter orbital period but it is synchronized. From a spectroscopic follow-up of TIC 137608661 we measure the radial velocities of the sdB star, determine its atmospheric parameters, and estimate the rotation rate at the surface of the star. This measurement allows us to exclude synchronized rotation also in the outer layers and suggests a differential rotation, with the surface rotating faster than the core, as found in few other similar systems. Furthermore, an analysis of the spectral energy distribution of TIC 137608661, together with a comparison between sdB pulsation properties and asteroseismic models, gives us further elements to constrain the system.

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Legendre, Christina M., Emil Damgaard‐Møller, Jacob Overgaard, and Dietmar Stalke. "The Quest for Optimal 3 d Orbital Splitting in Tetrahedral Cobalt Single‐Molecule Magnets Featuring Colossal Anisotropy and Hysteresis." European Journal of Inorganic Chemistry 2021, no. 30 (2021): 3108–14. http://dx.doi.org/10.1002/ejic.202100465.

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Gao, Yiting, Siping Wu, Guogang Shan та Gang Cheng. "Recent Progress in Blue Thermally Activated Delayed Fluorescence Emitters and Their Applications in OLEDs: Beyond Pure Organic Molecules with Twist D-π-A Structures". Micromachines 13, № 12 (2022): 2150. http://dx.doi.org/10.3390/mi13122150.

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Thermally activated delayed fluorescence (TADF) materials, which can harvest all excitons and emit light without the use of noble metals, are an appealing class of functional materials emerging as next-generation organic electroluminescent materials. Triplet excitons can be upconverted to the singlet state with the aid of ambient thermal energy under the reverse inter-system crossing owing to the small singlet–triplet splitting energy (ΔEST). This results from a specific molecular design consisting of minimal overlap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, due to the spatial separation of the electron-donating and electron-releasing part. When a well-designed device structure is applied, high-performance blue-emitting TADF organic light-emitting diodes can be realized with an appropriate molecular design. Unlike the previous literature that has reviewed general blue-emitting TADF materials, in this paper, we focus on materials other than pure organic molecules with twist D-π-A structures, including multi-resonance TADF, through-space charge transfer TADF, and metal-TADF materials. Cutting-edge molecules with extremely small and even negative ΔEST values are also introduced as candidates for next-generation TADF materials. In addition, OLED structures used to exploit the merits of the abovementioned TADF emitters are also described in this review.

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Bera, Kousik, Supratik Mukherjee, M. Mukadam, et al. "Selective electronic excitations in nearly half-metallic Heusler alloy NiFeMnSn—A Raman spectroscopic study." Applied Physics Letters 121, no. 5 (2022): 052404. http://dx.doi.org/10.1063/5.0097464.

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Half-metallic ferromagnetic full Heusler alloy NiFeMnSn is a promising material in spintronic device fabrication as it carries high spin polarization and high Curie temperature (Tc = 405 K). Understanding electronic excitations in a spin-polarized band structure is essential for the further use of this material in spin-based devices and to optimize the spin-dependent electronic structure in related compounds. In this Letter, we report electronic Raman scattering of NiFeMnSn with spectral signatures at a higher wavenumber than expected from the calculated phonon modes of the system. Temperature-dependent Raman spectroscopy demonstrates a non-monotonic behavior of the Raman shift with temperature across Tc. The orbital resolved electronic density of states and electronic band structure for both spin channels of the system, as obtained from the first principles density functional theory calculations, suggest that the observed Raman signatures originate from the Fe d orbital and its splitting due to the crystal field near the Fermi level. Furthermore, a strong magnetic field dependence of the spectral profile is observed. The study not only exhibits electronic Raman scattering in a Heusler alloy compound, which was unexplored to date, but also establishes Raman scattering as a promising probe to study the orbital-resolved partial density of states in the band structure near the Fermi level of a Heusler alloy.

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Sajjad, M., H. X. Zhang, N. A. Noor, S. M. Alay-e-Abbas, M. Abid, and A. Shaukat. "Half-metallic ferromagnetism in V-doped ZnTe semiconductor at reduced dopant concentration." Modern Physics Letters B 28, no. 13 (2014): 1450104. http://dx.doi.org/10.1142/s0217984914501048.

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In this study, we examine the structural, electronic, magnetic and bonding properties of zincblende phase Zn 1-x V x Te (x = 0.0625, 0.125, 0.25) compounds to present them as suitable candidates for spintronic applications. Density functional theory calculations have been used by implementing the accurate full-potential linear-augmented-planewave plus local-orbital method. Structural properties have been computed using Wu–Cohen generalized gradient approximation, whereas the modified Becke and Johnson local (spin) density approximation (mBJLDA) function has been employed for the evaluating ground state electronic properties and ferromagnetic behavior. The half-metallic (HM) ferromagnetism in Zn 1-x V x Te is analyzed in terms of V -3d states and it is shown that mBJLDA predicts wide HM gaps which promise the possibility of achieving V -doped ZnTe with high Curie temperature. The spin exchange splittings Δx(d) and Δx(pd) have been estimated and the contribution of conduction band (CB) and valence band (VB) in exchange splitting is calculated in terms of the exchange constants N0α and N0β. Furthermore, spin-polarized charge density calculation is presented for elucidating the bonding nature, while pressure dependence of total magnetic moment for three concentrations of V -doped ZnTe is also discussed.

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Wang, Xue Feng, Shao Yi Wu, Yue Xia Hu, and Pei Xu. "Studies of the Axial Shift and the Spin Hamiltonian Parameters for Mn²⁺ in a CdS Crystal." Defect and Diffusion Forum 294 (December 2009): 77–83. http://dx.doi.org/10.4028/www.scientific.net/ddf.294.77.

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The axial shift and the spin Hamiltonian parameters (zero-field splitting D, the g factors and the hyperfine structure constants A// and A) for Mn2+ in a CdS crystal are studied theoretically in this work. The calculations are carried out by using the perturbation formulae of these parameters for a 3d5 ion under trigonally distorted tetrahedra based upon the cluster approach, where the ligand orbital and spin-orbit coupling contributions are taken into account in a uniform way. From the studies, the impurity Mn2+ is found not to occupy the host Cd2+ site exactly but to experience a small outward shift of 0.018 Å away from the ligand triangle along the C3 axis. The above impurity axial shift leads to a much smaller trigonal distortion than the host Cd2+ site in CdS. The calculated spin Hamiltonian parameters are in reasonable agreement with the experimental data.

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Sakiyama, Hiroshi, Yuya Yamamoto, Ryusei Hoshikawa, and Ryoji Mitsuhashi. "Crystal Structures and Magnetic Properties of Diaquatetrapyridinenickel(II) and Diaquatetrapyridinecobalt(II) Complexes." Magnetochemistry 9, no. 1 (2022): 14. http://dx.doi.org/10.3390/magnetochemistry9010014.

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Metal complexes with pyridine ligands (py) have not been crystallographically characterized in large numbers, while a large number of 2,2′-bipyridine (bpy) complexes have been structurally characterized. Against this background of scarcity of py complexes, the aim of this study was to characterize the structures and magnetic properties of complexes with pyridine ligands. In this study, new py complexes, trans-[Ni(H2O)2(py)4][BPh4]2·4py (1) and trans-[Co(H2O)2(py)4][BPh4]2·4py (2), were prepared and characterized by the single-crystal X-ray diffraction method and magnetic measurements. In the crystal structure analysis, both complexes were found to have octahedral trans-N2O4 coordination geometry, and the coordination of the trans-aqua ligands was found to be enhanced by the hydrogen-bonded pyridine molecules as a base. In the simultaneous analysis of magnetic susceptibility and magnetization, both complexes were found to show strong magnetism in one direction (χz > χx, χy; Mz > Mx, My), and this was explained by the enhancement of the axial aqua ligands. In the nickel(II) complex, the strong axial ligand field was found to cause negative zero-field splitting (D < 0) to show the magnetic behavior, while in the cobalt(II) complex, the strong axial π-orbital effect was found to cause negative ligand field splitting (Δ) in the 4T1 ground state to show the magnetic behavior.

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Dom, Rekha, Hyun Gyu Kim, and Pramod H. Borse. "Investigation of Solar Photoelectrochemical Hydrogen Generation Ability of Ferrites for Energy Production." Materials Science Forum 764 (July 2013): 97–115. http://dx.doi.org/10.4028/www.scientific.net/msf.764.97.

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Ferrites have been predicted to be potential material for photo catalytic and photo electrochemical (PEC) hydrogen generation under visible light photons. The article briefly reviews, as well as compares the supremacy of ferrites over titanates and sulfides with respect to their photo-electro catalytic hydrogen producing ability. It shows that though the band energetic of a material plays a vital role to induce the photo-splitting of water; but its optical structure, at the first instance is very important to utilize it to absorb the visible light photons. Among all the PEC materials, the low-band gap ferrites (Fe-d orbital) favor absorption of visible light photons; at the same time offer an advantage of being an eco-friendly material system. A specific focus is given to the single phase, nanostructure and composite forms of typical ZnFe2O4system. Though a concise report, but also throws light on the importance and tunability of PEC properties.

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Titiš, Ján, Cyril Rajnák, and Roman Boča. "Energy Levels in Pentacoordinate d5 to d9 Complexes." Inorganics 10, no. 8 (2022): 116. http://dx.doi.org/10.3390/inorganics10080116.

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Energy levels of pentacoordinate d5 to d9 complexes were evaluated according to the generalized crystal field theory at three levels of sophistication for two limiting cases of pentacoordination: trigonal bipyramid and tetragonal pyramid. The electronic crystal field terms involve the interelectron repulsion and the crystal field potential; crystal field multiplets account for the spin–orbit interaction; and magnetic energy levels involve the orbital– and spin–Zeeman interactions with the magnetic field. The crystal field terms are labelled according to the irreducible representations of point groups D3h and C4v using Mulliken notation. The crystal field multiplets are labelled with the Bethe notations for the respective double groups D’3 and C’4. The magnetic functions, such as the temperature dependence of the effective magnetic moment and the field dependence of the magnetization, are evaluated by employing the apparatus of statistical thermodynamics as derivatives of the field-dependent partition function. When appropriate, the formalism of the spin Hamiltonian is applied, giving rise to a set of magnetic parameters, such as the zero-field splitting D and E, magnetogyric ratio tensor, and temperature-independent paramagnetism. The data calculated using GCFT were compared with the ab initio calculations at the CASSCF+NEVPT2 level and those involving the spin–orbit interaction.

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Pawlik, Tomasz, Daniel Michalik, Malgorzata Sopicka-Lizer та Stanisław Serkowski. "Influence of m and n Parameters of Ca-α-Sialon: Eu Solid Solution on Phosphor’s Optical Properties". Advances in Science and Technology 90 (жовтень 2014): 149–56. http://dx.doi.org/10.4028/www.scientific.net/ast.90.149.

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Ca-α-sialon doped by Eu2+ is a promising material for white LED phosphors due to the strong UV absorption and a yellow broad band emission of activator. The general formula of α sialon enables changing matrix composition by altering m (Al-N) and n (Al-O) parameters of cross-substitution. Changes of the neighboring Eu ligands in the host crystal lattice would trigger important modification of the photoluminescence properties because of different crystal field splitting and the energy of the d orbital. The aim of this study was to correlate the matrix solid solution parameters with photoluminescence spectra features. The specimens of Ca-α-sialon:Eu2+ with m, n parameters in the range of 0.5-2.5 and 0.25-1.25 respectively, were prepared by the solid state reaction method in the reducing atmosphere of a graphite furnace. The phase composition of the obtained specimens was characterized by XRD, microstructure and morphology by the SEM/EDS techniques. The photoluminescence spectra (excitation, emission) were also recorded. Results show that m/n parameters have a significant influence on the final optical properties.

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Tian, Di, Zhiwei Liu, Shengchun Shen, et al. "Manipulating Berry curvature of SrRuO3 thin films via epitaxial strain." Proceedings of the National Academy of Sciences 118, no. 18 (2021): e2101946118. http://dx.doi.org/10.1073/pnas.2101946118.

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Berry curvature plays a crucial role in exotic electronic states of quantum materials, such as the intrinsic anomalous Hall effect. As Berry curvature is highly sensitive to subtle changes of electronic band structures, it can be finely tuned via external stimulus. Here, we demonstrate in SrRuO3 thin films that both the magnitude and sign of anomalous Hall resistivity can be effectively controlled with epitaxial strain. Our first-principles calculations reveal that epitaxial strain induces an additional crystal field splitting and changes the order of Ru d orbital energies, which alters the Berry curvature and leads to the sign and magnitude change of anomalous Hall conductivity. Furthermore, we show that the rotation of the Ru magnetic moment in real space of a tensile-strained sample can result in an exotic nonmonotonic change of anomalous Hall resistivity with the sweeping of magnetic field, resembling the topological Hall effect observed in noncoplanar spin systems. These findings not only deepen our understanding of anomalous Hall effect in SrRuO3 systems but also provide an effective tuning knob to manipulate Berry curvature and related physical properties in a wide range of quantum materials.

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Matsushita, Toshio, Christel M. Marian, Rainer Klotz, and Sigrid D. Peyerimhoff. "Potential-energy curves, zero-field splittings, and radiative lifetimes for low-lying states of AsH." Canadian Journal of Physics 65, no. 2 (1987): 155–64. http://dx.doi.org/10.1139/p87-026.

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Large-scale multireference configuration-interaction (MRD-CI) calculations in an atomic-orbital (AO) basis set containing up to f functions on As and d on hydrogen are employed to study the potential-energy curves of the π2(X3Σ−, a1Δ, b1Σ+), the σ → π, and the π → σ3.1Π states; a large number of σ → σ* states; and the lowest π → s,p Rydberg series. The σ → σ* states are strongly repulsive and exhibit numerous interactions with the Rydberg members causing predissociation. The probabilities for the spin-forbidden transitions from b1Σ+and a1Δ to the X3Σ−ground state as well as the zero-field splittings of theX3Σ−and A3Π states have been evaluated by employing a variational perturbation scheme in which the zero-order wave functions are MRD-CI expansions. The perturber states are determined by their spin-orbit interactions, which are calculated by employing the Breit–Pauli one- and two-electron spin-orbit operator. The radiative lifetime of the b1Σ+ state is predicted to be 0.35 ms, whereby the dominant mechanism is deactivation to the ms = ±1 component.The parallel transition is found to be much weaker. The lifetime of a1Δ is calculated to be 22 ms, whereby the process [Formula: see text] is favored. Both b–X and a–X transitions borrow their intensity primarily from the A3Π–X3Σ− transition and, furthermore, the 1Π–a1Δ and higher 3,1Π state spin-allowed transitions. The probability for the quadrupole b–a transition is evaluated to be three orders of magnitude smaller than the b–X transition. The calculated zero-field splitting of the X3Σ− ground state amounts to 101.4 cm−1, and the fine-structure splitting between the 2, 1, and 0+ components of the A3Π state evaluated to be 544.5 and 674.4 cm−1, respectively, in good accord with experimental results; whereas the calculated Λ doubling of the0+–0− fine-structure levels of the A3Π state (35.2 cm−1 vs. 44.72 cm−1) is too small in the present treatment. The dependence of spin-orbit effects and transition probabilities on AO basis sets and relativistic corrections to the zero-order Hamiltonian are discussed, and it is concluded that lifetime calculations for spin-forbidden processes in first- and second-row molecules can be extended in a fairly straightforward manner to systems with considerable spin-orbit interactions.

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Rossi, T. C., D. Grolimund, O. Cannelli, et al. "X-ray absorption linear dichroism at the Ti K-edge of rutile (001) TiO2 single crystal." Journal of Synchrotron Radiation 27, no. 2 (2020): 425–35. http://dx.doi.org/10.1107/s160057752000051x.

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X-ray absorption linear dichroism of rutile TiO2 at the Ti K-edge provides information about the electronic states involved in the pre-edge transitions. Here, linear dichroism with high energy resolution is analyzed in combination with ab initio finite difference method calculations and spherical tensor analysis. It provides an assignment of the three pre-edge peaks beyond the octahedral crystal field splitting approximation and estimates the spatial extension of the corresponding final states. It is then discussed for the first time the X-ray absorption (XAS) of pentacoordinated titanium atoms due to oxygen vacancies and it is found that, similarly to anatase TiO2, rutile is expected to exhibit a transition on the low-energy side of peak A3. Its apparent absence in the experiment is related to the degree of p–d orbital mixing which is small in rutile due to its centrosymmetric point group. A recent XAS linear dichroism study on anatase TiO2 single crystals has shown that peak A2 has an intrinsic origin and is due to a quadrupolar transition to the 3d energy levels. In rutile, due to its centrosymmetric point group, the corresponding peak A2 has a small dipole moment explaining the weak transition. The results are confronted with recent picosecond X-ray absorption spectroscopy on rutile TiO2 nanoparticles.

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Arumugam, Krishnamoorthy, Devon Renock, and Udo Becker. "The basis for reevaluating the reactivity of pyrite surfaces: spin states and crystal field d-orbital splitting energies of bulk, terrace, edge, and corner Fe(ii) ions." Physical Chemistry Chemical Physics 21, no. 12 (2019): 6415–31. http://dx.doi.org/10.1039/c8cp05459b.

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Yao, Shukai, Babak Anasori, and Alejandro Strachan. "2D rare-earth metal carbides (MXenes) Mo₂NdC₂T₂ electronic structure and magnetic properties: A DFT + U study." Journal of Applied Physics 132, no. 20 (2022): 204301. http://dx.doi.org/10.1063/5.0124167.

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2D rare-earth metal carbides (MXenes) are attractive due to their novel electronic and magnetic properties and their potential as scalable 2D magnets. In this study, we used density functional theory with the Hubbard U correction to characterize the structure, termination, and magnetism in an out-of-plane ordered rare-earth containing M3C2T x MXene, Mo2NdC2T2 (T = O or OH). We investigated the effect of the U parameter on the stability and magnetism of two possible termination sites: the hollow sites aligned with the inner Nd atoms (Nd-hollow sites) and those aligned with the closest C atoms (C-hollow sites). We found that increasing UMo stabilized the Nd hollow sites, which minimized electrostatic repulsion between C and O atoms. Using UMo = 3.0 eV and UNd = 5.6 eV, obtained via the linear response method, we found that the energetically preferred termination site was C-hollow in Mo2NdC2O2 and Nd-hollow in Mo2NdC2(OH)2. Regardless of termination and the Hubbard U value, we found Mo2NdC2O2 and Mo2NdC2(OH)2 to be magnetic. The C-hollow termination resulted in ferromagnetic states for all Hubbard U tested with no magnetic moment in Mo. In the case of Nd-hollow, Mo became magnetic for UMo ≥ 4 eV. The difference of Mo magnetism in Nd-hollow and C-hollow was explained by crystal field splitting of the Mo d orbital caused by a distorted ligand.

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Silvotti, R., M. Uzundag, A. S. Baran, et al. "High-degree gravity modes in the single sdB star HD 4539." Monthly Notices of the Royal Astronomical Society 489, no. 4 (2019): 4791–801. http://dx.doi.org/10.1093/mnras/stz2244.

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ABSTRACT HD 4539 (alias PG 0044 + 097 or EPIC 220641886) is a bright (V = 10.2) long-period V1093 Her-type subdwarf B (sdB) pulsating star that was observed by the Kepler spacecraft in its secondary (K2) mission. We use the K2 light curve (78.7 d) to extract 169 pulsation frequencies, 124 with a robust detection. Most of these frequencies are found in the low-frequency region typical of gravity (g-)modes, but some higher frequencies corresponding to pressure (p-)modes are also detected. Therefore HD 4539 is a hybrid pulsator and both the deep and surface layers of the star can potentially be probed through asteroseismology. The lack of any frequency splitting in its amplitude spectrum suggests that HD 4539 has a rotation period longer than the K2 run and/or that it is seen pole-on. From asymptotic period spacing we see many high-degree modes, up to l = 12, in the spectrum of HD 4539, with amplitudes as low as a few ppm. A large fraction of these modes can be identified and for ∼29 per cent of them we obtain a unique and robust identification corresponding to l ≤ 8. Our study includes also a new determination of the atmospheric parameters of the star. From low-resolution spectroscopy we obtain Teff = 22 800 ± 160 K, log g = 5.20 ± 0.02, and log(N(He)/N(H)) = −2.34 ± 0.05. By fitting the SED we obtain Teff = 23 470$^{+650}_{-210}$ K, R⋆ = 0.26 ± 0.01 R⊙, and M⋆ = 0.40 ± 0.08 M⊙. Moreover, from 11 high-resolution spectra we see the radial velocity variations caused by the stellar pulsations, with amplitudes of ≈150 m s−1 for the main modes, and we can exclude the presence of a companion with a minimum mass higher than a few Jupiter masses for orbital periods below ∼300 d.

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Hu, Yong-Feng, G. Michael Bancroft, Kim H. Tan, John S. Tse, and Dong-Sheng Yang. "Variable-energy photoelectron spectroscopy of CpM(CO)3 (M = Mn, Re) and CpFe(CO)2I." Canadian Journal of Chemistry 74, no. 11 (1996): 2240–49. http://dx.doi.org/10.1139/v96-252.

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Photoelectron spectra of the valence, inner-valence, and core levels of CpM(CO)3 (M = Mn, Re) and CpFe(CO)2I were obtained using He I radiation and synchrotron radiation between 21 eV and 150 eV photon energies. The high-resolution Mn 3p, Fe 3p, and I 4d core level spectra are reported. Broadening of the I 4d spectrum is due to vibrational and ligand field splittings. Observation of the 3p spectra is critical to fully interpreting the np → nd resonance effect in the valence band spectra. This resonance effect is very useful for assigning the metal d orbital bands in the valence spectra. A Xα-SW calculation of CpMn(CO)3 was used to confirm the assignment of the valence and inner-valence orbitals. The experimental and theoretical branching ratios are in good agreement. The general trend of the metal d orbital ionization potentials for CpML3 (M = transition metal) complexes is also discussed. Key words: photoelectron, synchrotron radiation, CpMn(CO)3, CpRe(CO)3, CpFe(CO)2I, np → nd resonance, Xα-SW calculation.

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Tatarchuk, T. R., H. O. Sirenko, and U. L. Kush. "The Solution of Applied Problems of Complex Compounds with the d-Elements Central Atoms Surrounded by Octahedral Ligand Based on the Theory of Crystal Field." Фізика і хімія твердого тіла 16, no. 1 (2015): 145–54. http://dx.doi.org/10.15330/pcss.16.1.145-154.

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The crystal field theory as applied to complex compounds of d-elements surrounded by octahedral ligans was described. Ligand field causes the splitting of d-orbitals, which is characterized by the energy splitting Δo. The spectrochemical series of ligands and examples of high-spin and low-spin complex compounds depending on the degree of force field were presented. Deformation of octahedral complexes by the Jahn-Teller effect was described. It shows the calculation of gains power as a result of complex formation, called the crystal field stabilization energy (CFSE) depending on the electronic structure of the central ion and the ligand position in spectrochemical series. It shows the distribution of electrons in orbitals of eg and t2g complex ions with different electronic configurations (from d1 to d10), examples values of energy orbitals and energy of crystal field stabilization for high-spin and low-spin octahedral complexes.

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Ziatdinov, Albert M., Nikita S. Saenko та Peter G. Skrylnik. "REVERSIBLE CHANGES OF EDGE Π-ELECTRONIC STATES OF MULTILAYER GRAPHENE NANOCLUSTERS UNDER INFLUENCE OF ADSORBED CHLORINE MOLECULES". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 59, № 9 (2018): 4. http://dx.doi.org/10.6060/tcct.20165909.9y.

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The reversible decrease in the density of states of current carriers D(EF) at the Fermi level EF for nanographites - structural blocks of activated carbon fibers, at their interaction with adsorbed chlorine molecules, has been found. It has been shown that this effect can be explained by the spin-splitting of edge π-electronic states in nanographites induced by the enhancement of electron-electron interactions due to increase in the D(EF) at partial transfer of the electron density from adsorbent to adsorbate. The revealed irreversible decrease in the concentration of localized spins at nanographite chlorination indicates that the spins of electrons of unsaturated (dangling) σ-orbitals of edge carbon atoms and those of chlorine 3p-orbitals are coupled at this interaction, i.e. the edge covalent compound of nanographite with chlorine forms.

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Hanf, Schirin, Peter D. Matthews, Ning Li, He-Kuan Luo, and Dominic S. Wright. "The influence of halides in polyoxotitanate cages; dipole moment, splitting and expansion of d-orbitals and electron–electron repulsion." Dalton Transactions 46, no. 2 (2017): 578–85. http://dx.doi.org/10.1039/c6dt04288k.

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The influence of halides on the electronic structures of polyoxotitanate cages is explored in this experimental and theoretical study. Dipole moment, crystal-field splitting, Nephelauxetic influence of the halide and electron–electron repulsion all play a role.

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Ziatdinov, Albert M., Vladimir V. Kainara, and Nikita S. Saenko. "The Effect of Adsorbed Molecules on Electronic Structure and Magnetic Properties of Nanographites." Solid State Phenomena 247 (March 2016): 111–17. http://dx.doi.org/10.4028/www.scientific.net/ssp.247.111.

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The results of investigation of changes in electronic structure and magnetic properties of multilayer graphene nanoclusters (nanographites) occurring during their interaction with adsorbed chlorine molecules are presented. The found reversible decrease in the density of states of current carriers D(EF) at the Fermi energy EF can be explained by the spin-splitting of edge π-electron states in nanographites induced by the enhancement of electron-electron interactions due to increase of the D(EF) at partial transfer of the electron density from nanographites to chlorine adatoms. The revealed irreversible decrease in the concentration of localized spins indicates that the electron spins of 3p-orbitals of chlorine and unpaired (dundling) σ-orbitals of edge carbon atoms are coupled also at this interaction, i.e. the edge covalent compound of nanographite with chlorine forms. Character of changes in the spin-relaxation rate of π-electrons depending on the amount of adsorbed chlorine molecules and on temperature in chlorinated samples are also consistent with the above model of nanographite-chlorine interaction.

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Tran, Thi Nhan, Minh Triet Dang, Quang Huy Tran, Thi Theu Luong, and Van An Dinh. "Band valley modification under strain in monolayer WSe₂." AIP Advances 12, no. 11 (2022): 115023. http://dx.doi.org/10.1063/5.0127204.

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We study the band valley modification induced by isotropic strain in monolayer WSe2 using the non-local van der Waals density functionals theory including the spin–orbit coupling effect. The dominant contributions of orbitals to the band extrema, spin splitting, and exciton diversity in monolayer WSe2 are visually displayed. The vertical shift of the d and p partial orbitals of W and Se atoms, respectively, at band edges under strain results in a notable reduction of the bandgap. Under tensile strain, the deformations of the band valleys lead to an additional appearance of optical excitons and the disappearance of momentum excitons. Therefore, the experimental observations of the changes in the radiation spectra such as the redshift of A and B excitons, blueshift of C and D excitons, enhancement of intensity, localization, and symmetrization of the exciton resonances can be explained thoroughly. Under compression, the band valley modification may lead to an additional appearance of momentum excitons and the disappearance of optical excitons. The compression is predicted to cause the blueshift of A and B excitons while it brings the redshift to C and D excitons. An asymmetric broadening and intensity de-enhancement of the exciton resonances are also found when a compression strain is applied. The modification of the band valleys can be explained by the enhancement/reduction of hybridization between orbitals under strain. These results offer new perspectives to comprehend the appearance/disappearance of the excitons in monolayer transition metal dichalcogenide materials upon mechanical perturbation.

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Chiu, Ying-Nan. "Crystal-field theory for the Rydberg states of polyatomic molecules." Canadian Journal of Physics 64, no. 7 (1986): 782–95. http://dx.doi.org/10.1139/p86-140.

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The potential on a Rydberg electron due to the cluster of atoms near the center of a polyatomic molecule is expanded in powers of spherical harmonics. Nonvanishing potentials in totally symmetric irreducible representations are obtained using the crystal field of the cluster of atoms in D3h, C3v, D4v, C4v, Td, and D2d symmetries. Odd as well as the usual even powers of spherical harmonics are included up to [Formula: see text]. Spectroscopically observable differences in potentials between a planar versus a nonplanar XY3 molecule and among a square planar, pyramidal, tetrahedral, and dihedral XY4 molecule are exhibited. First-order energies are given for a Rydberg [Formula: see text] state showing λ dependence. Second-order energies due to mixing of Rydberg states by odd and even power potentials and splitting of ±λ degeneracies are shown analytically for an nd as well as an nf Rydberg electron. The formalism is applicable to nonpenetrating Rydberg orbitals. Approximate radial integrals are obtained. Exact angular integrals for the first- and second-order energies are given. Symmetry-adapted combinations of the separated Y3 and Y4 ligand atomic orbitals are derived up to d orbitals. The correlations between these linear combinations of atomic orbitals as molecular configurations change are shown, e.g., as an XY4 molecule distorts from (D4h, C4v) to (D2d, Td) and vice versa.

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de Biasi, R. S., and J. C. de Lima. "Ligand field splitting of d orbitals in nine-coordinated sites of capped antiprism structure: Application to monazite." Journal of Magnetism and Magnetic Materials 46, no. 3 (1985): 305–11. http://dx.doi.org/10.1016/0304-8853(85)90050-2.

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ZHANG, ZHI-HONG, SHAO-YI WU, CHUAN-JI FU, LI-HUA WEI, and XUE-FENG WANG. "THEORETICAL STUDIES OF THE LOCAL STRUCTURES AND SPIN HAMILTONIAN PARAMETERS FOR THE RHOMBICNi2+CENTERS INAgX(X=Cl,Br)." Modern Physics Letters B 23, no. 11 (2009): 1415–24. http://dx.doi.org/10.1142/s0217984909019545.

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The local structures and the spin Hamiltonian parameters (zero-field splittings D and E and the anisotropic g factors gx, gyand gz) for the rhombic Ni2+centers in AgX ( X = Cl , Br ) are theoretically studied from the perturbation formulas of these parameters for a 3d8ion under rhombically distorted octahedra. In these formulas, the ligand p- and s-orbital and spin-orbit coupling contributions are included on the basis of the cluster approach. The rhombic centers are attributed to the impurity Ni2+associated with one nearest-neighbor silver vacancy VAgalong the [110] direction as charge compensation. Based on the calculations, Ni2+is found to suffer an off-center displacement 0.092 Å (or 0.335 Å) for AgCl (or AgBr ) towards the VAgalong the [110] axis, while the ligands closest to the VAgundergo a small shift 0.065 Å (or 0.006 Å) away from (or towards) the VAg. The theoretical spin Hamiltonian parameters based on the above defect structures show good agreement with the experimental data.

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Hu, Yuwen, Hao Yang, Junjie Chen, Tuzhi Xiong, M. Sadeeq Jie Tang Balogun, and Yexiang Tong. "Efficient Hydrogen Evolution Activity and Overall Water Splitting of Metallic Co4N Nanowires through Tunable d-Orbitals with Ultrafast Incorporation of FeOOH." ACS Applied Materials & Interfaces 11, no. 5 (2019): 5152–58. http://dx.doi.org/10.1021/acsami.8b20717.

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Bai, Jing, Jiaying Ji, Liyu Hao, Tie Yang, and Xingwen Tan. "DFT Investigation on the Electronic, Magnetic, Mechanical Properties and Strain Effects of the Quaternary Compound Cu2FeSnS4." Crystals 10, no. 6 (2020): 509. http://dx.doi.org/10.3390/cryst10060509.

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The electronic, magnetic and mechanical properties of the quaternary compound Cu2FeSnS4 have been investigated with first principle calculations. Its half-metallicity has been identified with spin polarized band structures and its magnetic origination is caused by the strong spin splitting effect in the d orbitals of Fe atoms. The total magnetic moment of 4 μB is mainly contributed by the Fe atoms and the spatial distribution of the magnetic spin density and charge density difference have also been examined. Moreover, several mechanical properties of Cu2FeSnS4 have been derived and its mechanical stability is also verified. The directional dependent Young’s modulus exhibits relatively small anisotropy yet the shear modulus shows strong directional anisotropy. At last, the tetragonal strain effects have been evaluated and their impact on the electronic and magnetic properties are provided. Results show the total magnetic moment stays almost unchanged while the half-metallicity can only be maintained under relatively small variations for both strains. This study can provide comprehensive information about the various properties of Cu2FeSnS4 compound and serve as a helpful reference for its future applications.

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