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Journal articles on the topic 'Singlet and Triplet Potential Energy Surfaces (PES)'

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Published: 4 June 2021

Last updated: 6 February 2022

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1

Kutzelnigg, Werner, and Ralph Jaquet. "Explicitly correlated potential energy surface of , including relativistic and adiabatic corrections." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1848 (September 25, 2006): 2855–76. http://dx.doi.org/10.1098/rsta.2006.1871.

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After a short historical account of the theory of the ion, two ab initio methods are reviewed that allow the computation of the ground-state potential energy surface (PES) of in the Born–Oppenheimer (BO) approximation, with microhartree or even sub-microhartree accuracy, namely the R12 method and the method of explicitly correlated Gaussians. The BO-PES is improved by the inclusion of relativistic effects and adiabatic corrections. It is discussed how non-adiabatic effects on rotation and vibration can be simulated by corrections to the moving nuclear masses. The importance of the appropriate analytic fit to the computed points of the PES for the subsequent computation of the rovibronic spectrum is addressed. Some recent extensions of the computed PES in the energy region above the barrier to linearity are reviewed. This involves a large set of input geometries and the correct treatment of the dissociation asymptotics, including the coupling with the first excited singlet state. Some comments on this state as well as on the lowest triplet state of are made. The paper ends with a few remarks on the ion .

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2

Fosu, Emmanuel Adu, Collins Obuah, Louis Hamenu, Albert Aniagyei, Michael Kojo Ainooson, and Krishna K. Govender. "Quantum Mechanistic Studies of the Oxidation of Ethylene by Rhenium Oxo Complexes." Journal of Chemistry 2021 (August 21, 2021): 1–11. http://dx.doi.org/10.1155/2021/7931956.

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Transition-metal-mediated oxygen transfer reactions are of importance in both industry and academia; thus, a series of rhenium oxo complexes of the type ReO3L (L = O−, Cl−, F−, OH−, Br−, I−) and their effects as oxidation catalysts on ethylene have been studied. The activation and reaction energies for the addition pathways involving multiple spin states (singlet and triplet) have been computed. In all cases, structures on the singlet potential energy surfaces showed higher stability compared to their counterparts on the triplet potential energy surfaces (PESs). Frontier Molecular Orbital calculations show electrons flow from the HOMO of ethylene to the LUMO of rhenium for all complexes studied except ReO4− where the reverse case occurs. In the reaction between ReO3L (L = O−, Cl−, F−, OH−, Br−, and I−) and ethylene, the concerted [3 + 2] addition pathway on the singlet PES leading to the formation of dioxylate intermediate is favored over the [2 + 2] addition pathway leading to the formation of a metallaoxetane intermediate and subsequent rearrangement to the dioxylate. The activation and the reaction energies for the formation of the dioxylate on the singlet PES for the ligands studied followed the order O− > OH− > I− > F− > Br− > Cl− and O− > OH− > F− > I− > Br− > Cl−, respectively. Furthermore, the activation and the reaction energies for the formation of the metallaoxetane intermediate increase in the order O− > OH− > I− > Br− > Cl− > F− and O− > Br− > I− > Cl− > OH− > F−, respectively. The subsequent rearrangement of the metallaoxetane intermediate to the dioxylate is only feasible in the case of ReO4−. Of all the complexes studied, the best dioxylating catalyst is ReO3Cl (singlet surface) and the best epoxidation catalyst is ReO3F (singlet surface).

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3

Wu, Nan-Nan, Ming-Zhe Zhang, Shun-Li Ou-Yang, and Liang Li. "Theoretical Study of the C2H5 + HO2 Reaction: Mechanism and Kinetics." Molecules 23, no. 8 (August 1, 2018): 1919. http://dx.doi.org/10.3390/molecules23081919.

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The mechanism and kinetics for the reaction of the HO2 radical with the ethyl (C2H5) radical have been investigated theoretically. The electronic structure information of the potential energy surface (PES) is obtained at the MP2/6-311++G(d,p) level of theory, and the single-point energies are refined by the CCSD(T)/6-311+G(3df,2p) level of theory. The kinetics of the reaction with multiple channels have been studied by applying variational transition-state theory (VTST) and Rice–Ramsperger–Kassel–Marcus (RRKM) theory over wide temperature and pressure ranges (T = 220–3000 K; P = 1 × 10−4–100 bar). The calculated results show that the HO2 radical can attack C2H5 via a barrierless addition mechanism to form the energy-rich intermediate IM1 C2H5OOH (68.7 kcal/mol) on the singlet PES. The collisional stabilization intermediate IM1 is the predominant product of the reaction at high pressures and low temperatures, while the bimolecular product P1 C2H5O + OH becomes the primary product at lower pressures or higher temperatures. At the experimentally measured temperature 293 K and in the whole pressure range, the reaction yields P1 as major product, which is in good agreement with experiment results, and the branching ratios are predicted to change from 0.96 at 1 × 10−4 bar to 0.66 at 100 bar. Moreover, the direct H-abstraction product P16 C2H6 + 3O2 on the triplet PES is the secondary feasible product with a yield of 0.04 at the collisional limit of 293 K. The present results will be useful to gain deeper insight into the understanding of the kinetics of the C2H5 + HO2 reaction under atmospheric and practical combustion conditions.

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4

Mohajeri, A., and M. J. Jenabi. "Singlet and triplet potential energy surfaces of C3H2." Journal of Molecular Structure: THEOCHEM 820, no. 1-3 (October 2007): 65–73. http://dx.doi.org/10.1016/j.theochem.2007.06.005.

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5

Gordon, Mark S. "Potential-energy surfaces in singlet and triplet silylene." Chemical Physics Letters 114, no. 4 (March 1985): 348–52. http://dx.doi.org/10.1016/0009-2614(85)85097-1.

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6

Mawhinney, Robert C., and John D. Goddard. "Lowest Singlet and Triplet Potential Energy Surfaces of S2N2." Inorganic Chemistry 42, no. 20 (October 2003): 6323–37. http://dx.doi.org/10.1021/ic0301270.

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7

Goddard, John D. "Features of the thioformaldehyde potential energy surfaces." Canadian Journal of Chemistry 63, no. 7 (July 1, 1985): 1910–17. http://dx.doi.org/10.1139/v85-316.

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The structures of seven minima and five transition states of the S0 and T1 potential energy surfaces of thioformaldehyde have been located at the 3-21G* SCF level. Further calculations have been carried out to determine harmonic vibrational frequencies and to examine the effects of larger basis sets and of configuration interaction on energy differences. The molecular dissociation limit of H2 and CS is thermodynamically accessible at the energy of the lowest n,π* excited states and the singlet thiohydroxymethylenes lie only slightly too high. However, there are large barriers of ~85 to 90 kcal mol−1 to the molecular dissociation or to the 1,2-hydrogen shifts from thioformaldehyde to the thiohydroxymethylenes. The dissociation to H and HCS requires ~85.4 kcal mol−1 on the ground singlet and faces a barrier of several kcal mol−1 relative to products on the triplet surface. Any unimolecular photochemistry of thioformaldehyde is likely to require excitation to higher excited states than the lowest n,π* states.

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8

Cong-Jie, Zhang, Zhang Li-Ling, Cao Ze-Xing, and Zhang Qian-Er. "Isomerization Mechanisms of C5H2 on the Triplet and Singlet Potential Energy Surfaces." Chinese Journal of Chemistry 21, no. 2 (August 26, 2010): 117–20. http://dx.doi.org/10.1002/cjoc.20030210206.

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9

Pranata, Julianto, and Dennis A. Dougherty. "Theoretical studies of the singlet and triplet potential energy surfaces of cyclobutanediyl." Journal of Physical Organic Chemistry 2, no. 2 (March 1989): 161–76. http://dx.doi.org/10.1002/poc.610020208.

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10

Zuo, Junxiang, Bin Zhao, Hua Guo, and Daiqian Xie. "A global coupled cluster potential energy surface for HCl + OH ↔ Cl + H2O." Physical Chemistry Chemical Physics 19, no. 15 (2017): 9770–77. http://dx.doi.org/10.1039/c7cp00920h.

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A new and more accurate full-dimensional global potential energy surface (PES) for the ground electronic state of the ClH₂O system is developed by using the permutation invariant polynomial-neural network (PIP-NN) method to fit 15 777 points obtained using an explicitly correlated unrestricted coupled-cluster method with single, double, and perturbative triple excitations (UCCSD(T)-F12b).

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11

Froese, Robert D. J., and John D. Goddard. "Features of the lowest singlet and triplet potential energy surfaces of carbonate radical." Journal of Physical Chemistry 97, no. 29 (July 1993): 7484–90. http://dx.doi.org/10.1021/j100131a016.

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12

Duan, Hong-Guang, Ajay Jha, Xin Li, Vandana Tiwari, Hanyang Ye, Pabitra K. Nayak, Xiao-Lei Zhu, et al. "Intermolecular vibrations mediate ultrafast singlet fission." Science Advances 6, no. 38 (September 2020): eabb0052. http://dx.doi.org/10.1126/sciadv.abb0052.

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Singlet fission is a spin-allowed exciton multiplication process in organic semiconductors that converts one spin-singlet exciton to two triplet excitons. It offers the potential to enhance solar energy conversion by circumventing the Shockley-Queisser limit on efficiency. We study the primary steps of singlet fission in a pentacene film by using a combination of TG and 2D electronic spectroscopy complemented by quantum chemical and nonadiabatic dynamics calculations. We show that the coherent vibrational dynamics induces the ultrafast transition from the singlet excited electronic state to the triplet-pair state via a degeneracy of potential energy surfaces, i.e., a multidimensional conical intersection. Significant vibronic coupling of the electronic wave packet to a few key intermolecular rocking modes in the low-frequency region connect the excited singlet and triplet-pair states. Along with high-frequency local vibrations acting as tuning modes, they open a new channel for the ultrafast exciton transfer through the resulting conical intersection.

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13

Comeau, Donald C., Isaiah Shavitt, Per Jensen, and Philip R. Bunker. "Anabinitiodetermination of the potential‐energy surfaces and rotation–vibration energy levels of methylene in the lowest triplet and singlet states and the singlet–triplet splitting." Journal of Chemical Physics 90, no. 11 (June 1989): 6491–500. http://dx.doi.org/10.1063/1.456315.

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14

Luna, A., M. Manuel, O. Mo, and M. Yanez. "G2 ab Initio Calculations on the F+ + OH2 Singlet and Triplet Potential Energy Surfaces." Journal of Physical Chemistry 98, no. 28 (July 1994): 6980–87. http://dx.doi.org/10.1021/j100079a016.

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15

Froese, Robert D. J., and John D. Goddard. "Ab initio studies of the lowest singlet and triplet potential energy surfaces of CO2S." Molecular Physics 79, no. 4 (July 1993): 685–97. http://dx.doi.org/10.1080/00268979300101541.

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16

Tong, Yongchun, Qingyun Wang, Xinjian Xu, and Yongcheng Wang. "DFT Study of the Spin-Forbidden Reaction of N2O with CO Catalysed by Y+ Ions." Progress in Reaction Kinetics and Mechanism 42, no. 1 (February 2017): 1–7. http://dx.doi.org/10.3184/146867816x14799161258316.

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The mechanism of the cyclic reaction N2O(X1Σ+) + CO(1Σ+) → N2(X1Σg+) + CO2(1Σg+) catalysed by Y+ ions has been investigated on both singlet and triplet potential energy surfaces. The reactions were investigated by means of the relativistic effective core potential together with the Stuttgart basis sets on Y and the UB3LYP/6-311G** level of theory on non-metal atoms. The crossings involved between the singlet and triplet energy surfaces have been investigated by means of the intrinsic reaction coordinate approach used by Yoshizawa et al. Furthermore, both steps of the reaction are exothermic and the overall reaction is exothermic by 361.12 kJ mol−1.

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17

Cao, Zexing, Qianer Zhang, and Sigrid D. Peyerimhoff. "Theoretical Characterization of Photoisomerization Channels of Dimethylpyridines on the Singlet and Triplet Potential Energy Surfaces." Chemistry 7, no. 9 (May 4, 2001): 1927–35. http://dx.doi.org/10.1002/1521-3765(20010504)7:9<1927::aid-chem1927>3.0.co;2-p.

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18

Gao, Yang, Xiu-Juan Jia, Sha Li, Yan-Bo Yu, Rong-Shun Wang, and Xiu-Mei Pan. "Theoretical study on the singlet and triplet potential energy surfaces of NH (X3Σ−) + HCNO reaction." Theoretical Chemistry Accounts 127, no. 1-2 (January 6, 2010): 81–94. http://dx.doi.org/10.1007/s00214-009-0707-9.

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19

Lakshmanan, Sandhiya, Rene F. K. Spada, Francisco B. C. Machado, and William L. Hase. "Potential Energy Curves for Formation of the CH2O2 Criegee Intermediate on the 3CH2 + 3O2 Singlet and Triplet Potential Energy Surfaces." Journal of Physical Chemistry A 123, no. 41 (September 19, 2019): 8968–75. http://dx.doi.org/10.1021/acs.jpca.9b07368.

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20

Zhang, Yunju, Yizhen Tang, and Bing He. "Computational study on the mechanisms and kinetics of the CH2BrO2 + ClO reaction in the atmosphere." RSC Advances 10, no. 41 (2020): 24308–18. http://dx.doi.org/10.1039/c9ra10511e.

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21

Qutub, S., M. Derouich, Y. N. Kalugina, H. Asiri, and F. Lique. "Effect of isotropic collisions with neutral hydrogen on the polarization of the CN solar molecule." Monthly Notices of the Royal Astronomical Society 491, no. 1 (November 26, 2019): 1213–26. http://dx.doi.org/10.1093/mnras/stz3020.

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ABSTRACT In this work, we study the solar molecule CN, which presents conspicuous profiles of scattering polarization. We start by calculating accurate potential energy surfaces for the singlet and triplet electronic ground states in order to characterize the collisions between the CN molecule in its X 2Σ state and the hydrogen in its ground state 2S. The potential energy surfaces are included in the Schrödinger equation to obtain the scattering matrix and the probabilities of collisions. Depolarizing collisional rate coefficients are computed in the framework of the infinite order sudden approximation for temperatures ranging from T = 2000 K to T= 15 000 K. We give an interpretation of the results and compare the singlet and triplet collisional rate coefficients. We show that, for typical photospheric hydrogen density (nH = 1015−1016 cm−3), the X 2Σ state of CN is partially or completely depolarized by isotropic collisions.

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22

JIN, LIN, YI-HONG DING, and JIAN WANG. "REACTION MECHANISM OF THE CCN RADICAL WITH NITROGEN DIOXIDE." Journal of Theoretical and Computational Chemistry 06, no. 04 (December 2007): 661–74. http://dx.doi.org/10.1142/s0219633607003295.

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The complex singlet and triplet potential energy surfaces (PESs) of the [ C 2 N 2 O 2] system are performed at the B3LYP and Gaussian-3//B3LYP levels in order to investigate the possibility of the carbyne radical CCN in removal of nitrogen dioxide. Thirty minimum isomers and 36 transition states are located. Starting from the very energy-rich reactant R CCN + NO 2, the terminal C -attack adduct NCCN ( O ) O (singlet at -48.6 and triplet at -48.1 kcal/mol) is first formed on both singlet and triplet PESs. Subsequently, the singlet NCCN ( O ) O takes an O -transfer to form the intermediate singlet cis- NCC ( O ) NO (-120.1), which can lead to the fragments NCCO + NO (-94.4) without barrier. The simpler evolution of the triplet NCCN ( O ) O is the direct N – O rupture to form the final fragmentation NCCNO + 3 O (-31.0). However, the lower lying products 3 NCNO + CO (-103.3) and NCNCO + 3 O (-86.5) are kinetically much less competitive. All the involved transition states for the generation of NCCO + NO and NCCNO + 3 O lie much lower than the reactants, and it indicates that this reaction can proceed effectively even at low temperatures. We expect that the reaction CCN + NO 2 can play a role in both combustion and interstellar processes. Comparison is made between the CCN + NO 2 and CH + NO 2 reaction mechanisms.

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23

WENG, YA-NA, XIAO-JUAN YAN, and SHU-JIN LI. "THEORETICAL STUDY OF MECHANISM FOR THE ATMOSPHERIC REACTION CF3CHFO2 + NO." Journal of Theoretical and Computational Chemistry 12, no. 01 (February 2013): 1250101. http://dx.doi.org/10.1142/s0219633612501015.

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The mechanism of the reaction CF3CHFO2 + NO was investigated using ab initio and density functional theory (DFT). The optimized geometries for all stationary points on the reaction energy surface were calculated using MP2 and B3LYP methods with the aug-cc-pVDZ basis set. Single-point energy calculations were performed using the coupled cluster method with single, double and perturbative triple configurations, CCSD(T). The most important energy minima on the potential energy surface (PES) were found corresponding to two conformers of the peroxynitrite association adducts, cis- CF3CHFOONO and trans- CF3CHFOONO , and the nitrate, CF3CHFONO2 . The radical pairs ( CF3CHFO + NO2 ) and the nitrate are formed through the breaking of the peroxy bond of trans- CF3CHFOONO and the rearrangement of cis- CF3CHFOONO , respectively. The nitrate can be decomposed to carbonylated species ( CF3CHO or CF3CFO ), nitryl fluoride (NO2F), nitrous acid (HONO), and radical pairs ( CF3CHFO + NO2 ), which are of potential atmospheric importance.

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24

Schinke, R., and G. C. McBane. "Photodissociation of ozone in the Hartley band: Potential energy surfaces, nonadiabatic couplings, and singlet/triplet branching ratio." Journal of Chemical Physics 132, no. 4 (January 28, 2010): 044305. http://dx.doi.org/10.1063/1.3299249.

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25

Shayan, Kolsoom, and Morteza Vahedpour. "Computational mechanistic study of methanol and molecular oxygen reaction on the triplet and singlet potential energy surfaces." Structural Chemistry 24, no. 4 (September 27, 2012): 1051–62. http://dx.doi.org/10.1007/s11224-012-0128-6.

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26

Su, Ming-Der. "A Theoretical Characterization of the Photoisomerization Channels of 1,2-Cyclononadienes on both Singlet and Triplet Potential-Energy Surfaces." Chemistry - A European Journal 13, no. 35 (September 18, 2007): 9957–72. http://dx.doi.org/10.1002/chem.200700646.

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27

Asgharzade, Somaie, and Morteza Vahedpour. "Mechanism and rate constants for ammonia photochemical oxidation with O2 on the singlet and triplet potential energy surfaces." Structural Chemistry 25, no. 4 (December 6, 2013): 1057–65. http://dx.doi.org/10.1007/s11224-013-0375-1.

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28

Karami, Fereshte, and Morteza Vahedpour. "Computational mechanistic investigation of the gas phase C2H4 + CO reaction on the singlet and triplet potential energy surfaces." Journal of the Iranian Chemical Society 11, no. 3 (October 15, 2013): 781–90. http://dx.doi.org/10.1007/s13738-013-0352-z.

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29

Naouai, Manel, Abdelhak Jrad, Ayda Badri, and Faouzi Najar. "Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN." Monthly Notices of the Royal Astronomical Society 507, no. 4 (August 27, 2021): 5264–71. http://dx.doi.org/10.1093/mnras/stab2451.

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ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

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30

Silva, Pedro J. "Refining the reaction mechanism of O2towards its co-substrate in cofactor-free dioxygenases." PeerJ 4 (December 20, 2016): e2805. http://dx.doi.org/10.7717/peerj.2805.

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Cofactor-less oxygenases perform challenging catalytic reactions between singlet co-substrates and triplet oxygen, in spite of apparently violating the spin-conservation rule. In 1-H-3-hydroxy-4-oxoquinaldine-2,4-dioxygenase, the active site has been suggested by quantum chemical computations to fine tune triplet oxygen reactivity, allowing it to interact rapidly with its singlet substrate without the need for spin inversion, and in urate oxidase the reaction is thought to proceed through electron transfer from the deprotonated substrate to an aminoacid sidechain, which then feeds the electron to the oxygen molecule. In this work, we perform additional quantum chemical computations on these two systems to elucidate several intriguing features unaddressed by previous workers. These computations establish that in both enzymes the reaction proceeds through direct electron transfer from co-substrate to O2followed by radical recombination, instead of minimum-energy crossing points between singlet and triplet potential energy surfaces without formal electron transfer. The active site does not affect the reactivity of oxygen directly but is crucial for the generation of the deprotonated form of the co-substrates, which have redox potentials far below those of their protonated forms and therefore may transfer electrons to oxygen without sizeable thermodynamic barriers. This mechanism seems to be shared by most cofactor-less oxidases studied so far.

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31

Nunes, Cláudio M., Luís P. Viegas, Samuel A. Wood, José P. L. Roque, Robert J. McMahon, and Rui Fausto. "Heavy‐Atom Tunneling Through Crossing Potential Energy Surfaces: Cyclization of a Triplet 2‐Formylarylnitrene to a Singlet 2,1‐Benzisoxazole." Angewandte Chemie 132, no. 40 (August 7, 2020): 17775–80. http://dx.doi.org/10.1002/ange.202006640.

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Nunes, Cláudio M., Luís P. Viegas, Samuel A. Wood, José P. L. Roque, Robert J. McMahon, and Rui Fausto. "Heavy‐Atom Tunneling Through Crossing Potential Energy Surfaces: Cyclization of a Triplet 2‐Formylarylnitrene to a Singlet 2,1‐Benzisoxazole." Angewandte Chemie International Edition 59, no. 40 (August 11, 2020): 17622–27. http://dx.doi.org/10.1002/anie.202006640.

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33

Asgharzade, Somaie, Morteza Vahedpour, and Hamed Douroudgari. "Theoretical study on the mechanism of the N2H4 plus O2 reaction on the singlet and triplet potential energy surfaces." Computational and Theoretical Chemistry 1104 (March 2017): 47–55. http://dx.doi.org/10.1016/j.comptc.2017.02.007.

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34

Aguilera-Porta, Neus, Giovanni Granucci, Jordi Munoz-Muriedas, and Inés Corral. "Unveiling the photophysics of thiourea from CASPT2/CASSCF potential energy surfaces and singlet/triplet excited state molecular dynamics simulations." Computational and Theoretical Chemistry 1151 (March 2019): 36–42. http://dx.doi.org/10.1016/j.comptc.2019.01.026.

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35

Cai, Zheng-Li, David J. Tozer, and Jeffrey R. Reimers. "Time-dependent density-functional determination of arbitrary singlet and triplet excited-state potential energy surfaces: Application to the water molecule." Journal of Chemical Physics 113, no. 17 (November 2000): 7084–96. http://dx.doi.org/10.1063/1.1312826.

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36

Froese, Robert D. J., and John D. Goddard. "The COS2potential energy surface: Aspects of the lowest singlet and triplet potential energy surfaces for the reaction of oxygen atoms with carbon disulfide." Journal of Chemical Physics 98, no. 7 (April 1993): 5566–78. http://dx.doi.org/10.1063/1.464903.

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37

Harvey, Jeremy N., Massimiliano Aschi, Helmut Schwarz, and Wolfram Koch. "The singlet and triplet states of phenyl cation. A hybrid approach for locating minimum energy crossing points between non-interacting potential energy surfaces." Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta) 99, no. 2 (April 20, 1998): 95–99. http://dx.doi.org/10.1007/s002140050309.

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38

Ou Yang, ShunLi, NanNan Wu, JingYao Liu, and XiangGang Han. "Theoretical Mechanism Study on the Reaction of FOO Radical with NO." Journal of Chemistry 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/5387853.

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The mechanism for the reaction of radical FOO with NO was investigated theoretically. The electronic structure information for the singlet potential energy surfaces (PES) was obtained at the MP2/6-311+G(2df) level of theory, and the single-point energies were refined by the CCSD(T)/6-311+G(2df) level. The rate constants as well as the pressure and temperature dependence of various product channels for the reaction are predicted. The calculated results show that starting from the energy-rich intermediateFOONOtp(IM1), at room temperature 298 K and at 1 Torr, FNO is the exclusive product which is consistent with the experimental results. The present results will be useful to gain a deep insight into the reaction mechanism of FOO + NO reaction.

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39

Vincent, Mark A., and Ian H. Hillier. "Structures on the Singlet and Triplet O3H2 Potential Energy Surfaces: Implications for Photonucleation of Water in the Presence of Molecular Oxygen." Journal of Physical Chemistry 99, no. 10 (March 1995): 3109–13. http://dx.doi.org/10.1021/j100010a021.

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40

Langhoff, S. R., D. W. Schwenke, and H. Partridge. "Determination of opacity data bases for TiO and H2O." Symposium - International Astronomical Union 178 (1997): 295–303. http://dx.doi.org/10.1017/s007418090000944x.

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Current ab initio methods for determining potential energy surfaces are discussed in relation to the TiO and H2O molecules, both of which make important contributions to the opacity of M-type stars. For the TiO molecule we discuss the determination of the radiative lifetimes of the excited states and band oscillator strengths for both the triplet and singlet band systems. While the theoretical radiative lifetimes for TiO agree well with recent measurements, the band oscillator strengths differ significantly from those currently employed in opacity calculations. For the H2O molecule we discuss the current results for the ground state potential energy and dipole moment surfaces generated at NASA Ames. We show that it is necessary to account for such effects as core-valence correlation to generate a potential energy surface of near spectroscopic accuracy. The current status of our effort to establish opacity data bases for both TiO and H2O is described.

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41

Buntine, Mark A., Chansik Lee, and Gregory F. Metha. "The lowest-lying excited singlet and triplet electronic states of propanal: an ab initio molecular orbital investigation of the potential energy surfaces." Physical Chemistry Chemical Physics 6, no. 4 (2004): 688. http://dx.doi.org/10.1039/b313777e.

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42

Mebel, A. M., A. Luna, M. C. Lin, and K. Morokuma. "A density functional study of the global potential energy surfaces of the [H,C,N,O] system in singlet and triplet states." Journal of Chemical Physics 105, no. 15 (October 15, 1996): 6439–54. http://dx.doi.org/10.1063/1.472494.

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43

Cruz, Elso M., Xabier Lopez, Mirari Ayerbe, and Jesus M. Ugalde. "G2 Study of the Triplet and Singlet [H3, P2]+Potential Energy Surfaces. Mechanisms for the Reaction of P+(1D,3P) with PH3." Journal of Physical Chemistry A 101, no. 11 (March 1997): 2166–72. http://dx.doi.org/10.1021/jp962357o.

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44

Hoffmann, Alexander, and Sonja Herres-Pawlis. "Hiking on the potential energy surface of a functional tyrosinase model – implications of singlet, broken-symmetry and triplet description." Chem. Commun. 50, no. 4 (2014): 403–5. http://dx.doi.org/10.1039/c3cc46893c.

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45

Takayanagi, Toshiyuki, Yuya Watabe, and Takaaki Miyazaki. "Reduced-Dimensionality Quantum Dynamics Study of the 3Fe(CO)4 + H2 → 1FeH2(CO)4 Spin-inversion Reaction." Molecules 25, no. 4 (February 17, 2020): 882. http://dx.doi.org/10.3390/molecules25040882.

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Many chemical reactions of transition metal compounds involve a change in spin state via spin inversion, which is induced by relativistic spin-orbit coupling. In this work, we theoretically study the efficiency of a typical spin-inversion reaction, 3Fe(CO)4 + H2 → 1FeH2(CO)4. Structural and vibrational information on the spin-inversion point, obtained through the spin-coupled Hamiltonian approach, is used to construct three degree-of-freedom potential energy surfaces and to obtain singlet-triplet spin-orbit couplings. Using the developed spin-diabatic potential energy surfaces in reduced dimensions, we perform quantum nonadiabatic transition state wave packet calculations to obtain the cumulative reaction probability. The calculated cumulative reaction probability is found to be significantly larger than that estimated from the one-dimensional surface-hopping probability. This indicates the importance of both multidimensional and nuclear quantum effects in spin inversion for polyatomic chemical reaction systems.

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46

SÜLZLE, D., and C. CHANG. "VESH: A VERTICAL ENERGY SURFACE HOPPING PROCEDURE FOR DETERMINING STABLE ISOMERS OF POLYATOMIC MOLECULAR SYSTEMS." International Journal of Modern Physics C 10, no. 07 (October 1999): 1229–36. http://dx.doi.org/10.1142/s0129183199000991.

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We describe a heuristic algorithmic procedure by which a large number of points of minimal energy in configuration space of a polyatomic molecular system (isomers) can be determined. Making use of the intrinsic electronic structure energy scheme of the molecular system, the procedure is initiated from an arbitrary starting configuration and progresses via successive vertical spin, and/or charge state shifts with interposed optimization steps. In this systematic way, a great manifold of stable isomers not only on the ground state potential energy surface but also on excited spin and charge state surfaces can be located. The efficiency and computational practicability of the procedure has been tested on various examples. In these cases, the global minima have been found. Results for singlet and triplet states of the system P 4 are presented in detail.

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XU, FANG. "APPLICATIONS OF COLLISIONALLY EXCITED AUTOIONIZATION ELECTRON SPECTROSCOPY: CASE STUDIES OF Na ADSORPTION AND OXYGEN COADSORPTION ON METAL SURFACES." Modern Physics Letters B 09, no. 06 (March 10, 1995): 319–41. http://dx.doi.org/10.1142/s0217984995000310.

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We discuss the mechanism and applications of the low energy collisionally excited projectile and target atom autoionization electron spectroscopy through illustration of the representative case studies of Na adsorption and O 2 coadsorption on polycrystalline Cr, Pt, and Al substrates using 700 eV Ne + ion impact. We show that it is possible to determine the surface electrostatic potentials with the detected electron kinetic energies, to monitor the evolution of the local valence charge distribution around the excitation sites with the coverage dependence of the Ne 2p 41 D -3 P singlet-to-triplet conversion rate, and to establish the overlayer growth morphology with the variation of the widths and relative intensities of the transition lines. We demonstrate the great potential of this surface analysis technique in the studies of interface formation involving alkali metal overlayers.

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Khadri, F., A. Chefai, and K. Hammami. "Low-temperature rate constants and radiative transfer for rotational de-excitation of C5S by collision with He." Monthly Notices of the Royal Astronomical Society 498, no. 4 (September 10, 2020): 5159–65. http://dx.doi.org/10.1093/mnras/staa2746.

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ABSTRACT The C5S molecule is the largest member of the series of sulphur-containing carbon chains CnS observed in space. Given the lack of data concerning this molecule, we computed rate coefficients of C5S(1Σ+) induced by collision with He. These rates are obtained for thermal temperature below 100 K by mean of a new two-dimensional potential energy surface (PES) calculated with the explicit correlated coupled cluster with single, double, and pertubative triple excitation (ccsd(t)-f12) ab initio approach and the aug-cc-pVTZ basis sets. The C5S–He PES presents three minimums of −59.726, −55.355, and −36.506 cm−1 below its dissociation limit. Using this PES, the integral cross-sections are performed in the close-coupling (CC) and coupled-state (CS) quantum time independent formalisms for $E_\mathrm{ c}\le 500 \, \mathrm{ cm}^{-1}$ and J ≤ 13 (for CC) and J ≤ 50 (for CS). By averaging these cross-sections we obtained the downward rate coefficients. The new collisional data are used to simulate the excitation of C5S in the circumstellar gas. We obtain the excitation and brightness temperatures of the four lines observed towards the IRC+10216 which confirms the necessity of using radiative transfer calculations to accurately determine C5S abundance since the local thermodynamic equilibrium conditions are not fulfilled. The new collisional data should help to estimate the abundance of C5S in several interstellar regions.

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Park, Won K., Joonho Park, Seung C. Park, Bastiaan J. Braams, Chao Chen, and Joel M. Bowman. "Quasiclassical trajectory calculations of the reaction C+C2H2→l-C3H, c-C3H+H, C3+H2 using full-dimensional triplet and singlet potential energy surfaces." Journal of Chemical Physics 125, no. 8 (August 28, 2006): 081101. http://dx.doi.org/10.1063/1.2333487.

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Boyle, Jason M., David M. Bell, Scott L. Anderson, and A. A. Viggiano. "Reaction of HOD+with NO2: Effects of OD and OH Stretching, Bending, and Collision Energy on Reactions on the Singlet and Triplet Potential Surfaces." Journal of Physical Chemistry A 115, no. 7 (February 24, 2011): 1172–85. http://dx.doi.org/10.1021/jp110523s.

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