Articoli di riviste: "ENERGY MOLECULES"

1

Willich, Marcel M., Lucas Wegener, Johannes Vornweg, Manuel Hohgardt, Julia Nowak, Mario Wolter, Christoph R. Jacob e Peter Jomo Walla. "A new ultrafast energy funneling material harvests three times more diffusive solar energy for GaInP photovoltaics". Proceedings of the National Academy of Sciences 117, n. 52 (14 dicembre 2020): 32929–38. http://dx.doi.org/10.1073/pnas.2019198117.

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There is no theoretical limit in using molecular networks to harvest diffusive sun photons on large areas and funnel them onto much smaller areas of highly efficient but also precious energy-converting materials. The most effective concept reported so far is based on a pool of randomly oriented, light-harvesting donor molecules that funnel all excitation quanta by ultrafast energy transfer to individual light-redirecting acceptor molecules oriented parallel to the energy converters. However, the best practical light-harvesting system could only be discovered by empirical screening of molecules that either align or not within stretched polymers and the maximum absorption wavelength of the empirical system was far away from the solar maximum. No molecular property was known explaining why certain molecules would align very effectively whereas similar molecules did not. Here, we first explore what molecular properties are responsible for a molecule to be aligned. We found a parameter derived directly from the molecular structure with a high predictive power for the alignability. In addition, we found a set of ultrafast funneling molecules that harvest three times more energy in the solar’s spectrum peak for GaInP photovoltaics. A detailed study on the ultrafast dipole moment reorientation dynamics demonstrates that refocusing of the diffusive light is based on ∼15-ps initial dipole moment depolarization followed by ∼50-ps repolarization into desired directions. This provides a detailed understanding of the molecular depolarization/repolarization processes responsible for refocusing diffusively scattered photons without violating the second law of thermodynamics.

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Yu, Chang Feng. "A Novel High Precision Analytic Potential Function for Diatomic Molecules". Key Engineering Materials 645-646 (maggio 2015): 313–18. http://dx.doi.org/10.4028/www.scientific.net/kem.645-646.313.

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A new analytical potential energy functions is presented, the potential energy function is examined by 13 examples of different diatomic molecules or ions——homonuclear ground-state for neutral diatomic molecules, heternuclear ground-state for charged diatomic molecular ion, heternuclear excitation-state neutral diatomic molecules ,heternuclear excited-state for charged diatomic molecular ion, homonuclear excited-state for neutral diatomic molecule , homonuclear excited-state for charged diatomic moleculeetc.. as a consequence, the theoretical values of the vibrational energy level of molecules calculated by the potential energy function are in high-precision consistent with RKR data (Rydberg-Klein-Rees) or experimental data.

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Borodin, Dmitriy, Igor Rahinov, Pranav R. Shirhatti, Meng Huang, Alexander Kandratsenka, Daniel J. Auerbach, Tianli Zhong et al. "Following the microscopic pathway to adsorption through chemisorption and physisorption wells". Science 369, n. 6510 (17 settembre 2020): 1461–65. http://dx.doi.org/10.1126/science.abc9581.

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Adsorption involves molecules colliding at the surface of a solid and losing their incidence energy by traversing a dynamical pathway to equilibrium. The interactions responsible for energy loss generally include both chemical bond formation (chemisorption) and nonbonding interactions (physisorption). In this work, we present experiments that revealed a quantitative energy landscape and the microscopic pathways underlying a molecule’s equilibration with a surface in a prototypical system: CO adsorption on Au(111). Although the minimum energy state was physisorbed, initial capture of the gas-phase molecule, dosed with an energetic molecular beam, was into a metastable chemisorption state. Subsequent thermal decay of the chemisorbed state led molecules to the physisorption minimum. We found, through detailed balance, that thermal adsorption into both binding states was important at all temperatures.

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MATSUI, A. H., M. TAKESHIMA, K. MIZUNO e T. AOKI-MATSUMOTO. "PHOTOPHYSICAL OVERVIEW OF EXCITATION ENERGY TRANSFER IN ORGANIC MOLECULAR ASSEMBLIES — A ROUTE TO STUDY BIO-MOLECULAR ARRAYS —". International Journal of Modern Physics B 15, n. 28n30 (10 dicembre 2001): 3857–60. http://dx.doi.org/10.1142/s0217979201008846.

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Excitonic processes in organic molecular crystals are discussed in terms of two parameters, the crystal size and the constituent molecule size. From the luminescence and absorption spectra of a series of aromatic molecular crystals we find a systematic change in exciton energy transport as functions of the size of crystal and its constituent molecule size. Characteristic features of bulk crystals and microcrystallites are as follows. (1) In bulk crystals exciton energy transport depends on the constituent molecule size. When molecules are small, the exciton energy transport occurs by free excitons, but when molecules are large free exciton transport disappears because excitons get self-trapped. (2) In microcrystallites, exciton energy transport depends on the crystallite size. When the size is larger than a critical one, excitons travel as quantum mechanical waves but when the size is smaller than the critical one the exciton waves get confined within the crystallite. The results are independent of the chemical species of constituent molecules and thus applicable to novel molecular arrays such as biological molecular arrays.

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Mehboob, Muhammad Yasir, Muhammad Usman Khan, Riaz Hussain, Rafia Fatima, Zobia Irshad e Muhammad Adnan. "Designing of near-infrared sensitive asymmetric small molecular donors for high-efficiency organic solar cells". Journal of Theoretical and Computational Chemistry 19, n. 08 (18 settembre 2020): 2050034. http://dx.doi.org/10.1142/s0219633620500340.

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Herein, we have designed four small molecular donors (SMDs) with Donor–Acceptor–Acceptor (D–Á–A) backbone having different acceptor units for highly efficient organic solar cells (OSCs). The specific molecular modeling has been made by replacing the additional acceptor unit (A) of recently synthesized TPA-DAA-MDN molecule (R) by employing different highly efficient acceptor units in order to improve the photovoltaic performances of the molecules. A theoretical approach (DFT and TD-DFT) has been applied to investigate the photophysical, opto-electronic and photovoltaic parameters of the designed molecules (DAA1–DAA4) and compared with the reference molecule (R). The red-shifting absorption of SMDs is the most important factor for highly efficient OSCs. Our all formulated molecules showed a red shifted absorption spectrum and also exhibit near IR sensitivity. Acceptor unit modification of R molecule causes reduction in HOMO-LUMO energy gap; therefore, all designed molecules offer better opto-electronic properties as compared to R molecule. A variety of certain critical factors essential for efficient SMDs like frontier molecular orbitals (FMOs), absorption maxima, dipole moment, exciton binding energy along with transition density matrix, excitation energy, open circuit voltages and charge mobilities of (DAA1–DAA4) and R have also been investigated. Generally, low values of reorganizational energy (hole and electron) offer high charge mobility and our all designed molecules are enriched in this aspect. High open circuit voltage values, low excitation energies, large dipole moment values indicate that our designed SMDs are suitable candidates for high-efficiency OSCs. Furthermore, conceptualized molecules are superior and thus are suggested to experimentalist for out-looking future progresses of highly efficient OSCs devices.

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Mishra, Mirtunjai, Narinder Kumar, Khem Thapa, B. S. Rawat, Reena Dhyani, Devendra Singh e Devesh Kumar. "Physical, chemical, optical and insulating properties of alkyl benzoic acid derivatives liquid crystal due to extension alkyl chain (CNH2N+1) length: A DFT study". Kragujevac Journal of Science, n. 45 (2023): 21–28. http://dx.doi.org/10.5937/kgjsci2345021m.

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The aim of this paper was to analyze the structure, vibrations and to do global analyses of molecules of p-n-alkyl benzoic acid (nBAC). The energy, IR, and Homo-Lumo optimised parameters were calculated using a density functional method. The global reactivity descriptors of molecules, including electro-negativity, electron affinity, ionisation potential, global softness, chemical potential, and energy gaps is further shown by band gap value drops. It offers important details on the stability of nBAC molecules (n=4,5,6,7,8,9). It has been demonstrated that the molecular series displays the energy of an isolated molecule as the length of the alkyl chain rises. The molecular series is useful for insulating applications since it also has a high band gap.

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Sivanathan, M., e B. Karthikeyan. "Computational Studies of Self Assembled 3,5 Bis(Tri Fluoro Methyl) Benzyl Amine Phenyl Alanine Nano Tubes". Materials Science Forum 1070 (13 ottobre 2022): 105–13. http://dx.doi.org/10.4028/p-ftw4x6.

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In this work 3,5 Bis(Tri fluro methyl)Benzyl amine phenyl alanine a monmer molecule is DFT theoretically optimized to get the structural insight of the molecule. Band gap energy, Mullikan atomic charges, DOS spectral analysis, HOMO - LUMO, Electrostatic surface potential , molecular electrostatic potential and theoretical Raman spectral analysis is computed and compared with the experimental data .Since this molecule shows self assembly similar to peptide molecules it is quite interesting to analyze its structure based on theory and experimental the results suggests the H –boding interactions between the molecules is the key mechanism. The band energy from DOS plots suggests the molecular interactions through π-π .The possibility of the self assembly is explained further from Raman spectral studies that tells the mode specific interaction among the molecules..

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Jungclas, Hartmut, Viacheslav V. Komarov, Anna M. Popova e Lothar Schmidt. "Pyrene Fluorescence in Nanoaggregates Irradiated by IR Photons". Zeitschrift für Naturforschung A 69, n. 12 (1 dicembre 2014): 629–34. http://dx.doi.org/10.5560/zna.2014-0069.

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AbstractPyrene fluorescence of a molecular donor-acceptor nanoaggregate induced by infrared (IR) radiation with λ =16 - 18 μm considered.We assume that this nanoaggregate consists of two molecules, exchanging energy by dipole-dipole interaction. The energy acceptor is an aromatic molecule. The other molecule, the energy donor, is assumed to contain a substructure CnH2n which serves as antenna for IR radiation. The antenna can accumulate collective vibrational excitations and transmit them to the acceptor molecule. Acceptor fluorescence is possible if the amount of transmitted energy is equal to the energy of its excited state in the visible part of the absorption spectrum. We analyse the fluorescence of a nanoaggregate consisting of a donor with a C5H10 substructure and pyrene molecules or pyrene dimers as acceptors. A method is proposed for determination of the ‘critical micelle concentration’ (CMC), i. e. concentration of a dissolved polymer, for which the polymer molecules are beginning to aggregate.

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Gajdoš, Ján, e Tomáš Bleha. "Stability of molecular aggregates of hydrocarbons with all-trans chains and translation of the molecules". Collection of Czechoslovak Chemical Communications 50, n. 7 (1985): 1553–64. http://dx.doi.org/10.1135/cccc19851553.

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Potential energy has been calculated for molecular aggregates formed of all-trans extended hexanes with various arrangements of the central molecule surrounded by the first coordination sphere. Differences in stabilities of the aggregates are connected with biaxial character of asymmetry of the interaction energy of extended paraffins. When investigating the multiparameter interaction potential of the partially ordered systems of hydrocarbon chains, the first step consisted in determination of the energy barriers to longitudinal shifts of the central molecules at various distances of the surrounding molecules. Destabilization of the aggregates with displaced molecules is due to both the mismatch of the central molecule to the matrix and effective shortening of that part of the central molecule which is "immersed" in the aggregate. The energetics of the model aggregates is made use of in elucidating the role of translation of paraffins and cognate molecules in rotational phase, in mesophases, and at a forced shortening of the chains connected with conformational transition.

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Lu, Peifen, Junping Wang, Hui Li, Kang Lin, Xiaochun Gong, Qiying Song, Qinying Ji et al. "High-order above-threshold dissociation of molecules". Proceedings of the National Academy of Sciences 115, n. 9 (13 febbraio 2018): 2049–53. http://dx.doi.org/10.1073/pnas.1719481115.

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Electrons bound to atoms or molecules can simultaneously absorb multiple photons via the above-threshold ionization featured with discrete peaks in the photoelectron spectrum on account of the quantized nature of the light energy. Analogously, the above-threshold dissociation of molecules has been proposed to address the multiple-photon energy deposition in the nuclei of molecules. In this case, nuclear energy spectra consisting of photon-energy spaced peaks exceeding the binding energy of the molecular bond are predicted. Although the observation of such phenomena is difficult, this scenario is nevertheless logical and is based on the fundamental laws. Here, we report conclusive experimental observation of high-order above-threshold dissociation of H2 in strong laser fields where the tunneling-ionized electron transfers the absorbed multiphoton energy, which is above the ionization threshold to the nuclei via the field-driven inelastic rescattering. Our results provide an unambiguous evidence that the electron and nuclei of a molecule as a whole absorb multiple photons, and thus above-threshold ionization and above-threshold dissociation must appear simultaneously, which is the cornerstone of the nowadays strong-field molecular physics.

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Siegmann, B., U. Werner e H. O. Lutz. "Multiple Ionisation and Fragmentation of Molecules". Australian Journal of Physics 52, n. 3 (1999): 545. http://dx.doi.org/10.1071/ph98089.

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The multiple ionisation and dissociation of molecules, e.g. H2, N2, H2O, CH4 and C60, by fast ions was studied using a position- and time-sensitive multi-particle detector. The data obtained allow a clear separation of various reaction channels. Of special interest are the ‘Coulomb explosion’ processes like N2 → Nq+ +Nn+ or H2O → H+ + H+ +On+. For these reactions the coincident measurement of the momenta of correlated fragment ion yields a kinematically complete image of the molecular break-up process, and the fragmentation energy as well as angular correlations can be derived for each individual event. In the case of H2 as target molecule the CE model describes the fragmentation energy rather well, whereas in the case of more complex molecules, e.g. N2, CO and CH4, the simple CE model is insufficient to explain the measured energy and angular spectra. Better agreement was achieved with ab initio MCSCF calculations which take into account several molecular states of the fragmenting highly charged molecular ion.

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Liu, Qing Zhi, Deng Feng Yang, Ya Juan Yue, Zhen Bo Geng e Yang Dong Hu. "Molecular Simulation of Solution Process of Organic Molecules in Polyethylene Membranes". Advanced Materials Research 781-784 (settembre 2013): 452–57. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.452.

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The dissolution process of benzene, toluene and ethylbenzene in amorphous polyethylene (PE) membrane was studied in this paper, and the solubility coefficients of the above organic molecules were analyzed and calculated by molecular dynamics simulation. The results showed: the solubility coefficient decreased with increasing molecular weights of organic molecules in the same temperature, and it also decreased with increasing temperature for the same organic molecule. Distribution of density field and energy field for organic molecules in PE were obtained. From the density distribution, the concentrated adsorbed area of the three kinds of molecules is clearly seen, which located at the more loose place in polyethylene membrane. From the energy distribution, it showed thehot spots of the organic molecules, which were the location that the organic molecules were most easily absorbed. The adsorption capacities of benzene, toluene and ethyl benzene in polyethylene membrane decreased in turn.

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Takatsuka, Kazuo. "Quantum Chaos in the Dynamics of Molecules". Entropy 25, n. 1 (29 dicembre 2022): 63. http://dx.doi.org/10.3390/e25010063.

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Quantum chaos is reviewed from the viewpoint of “what is molecule?”, particularly placing emphasis on their dynamics. Molecules are composed of heavy nuclei and light electrons, and thereby the very basic molecular theory due to Born and Oppenheimer gives a view that quantum electronic states provide potential functions working on nuclei, which in turn are often treated classically or semiclassically. Therefore, the classic study of chaos in molecular science began with those nuclear dynamics particularly about the vibrational energy randomization within a molecule. Statistical laws in probabilities and rates of chemical reactions even for small molecules of several atoms are among the chemical phenomena requiring the notion of chaos. Particularly the dynamics behind unimolecular decomposition are referred to as Intra-molecular Vibrational energy Redistribution (IVR). Semiclassical mechanics is also one of the main research fields of quantum chaos. We herein demonstrate chaos that appears only in semiclassical and full quantum dynamics. A fundamental phenomenon possibly giving birth to quantum chaos is “bifurcation and merging” of quantum wavepackets, rather than “stretching and folding” of the baker’s transformation and the horseshoe map as a geometrical foundation of classical chaos. Such wavepacket bifurcation and merging are indeed experimentally measurable as we showed before in the series of studies on real-time probing of nonadiabatic chemical reactions. After tracking these aspects of molecular chaos, we will explore quantum chaos found in nonadiabatic electron wavepacket dynamics, which emerges in the realm far beyond the Born-Oppenheimer paradigm. In this class of chaos, we propose a notion of Intra-molecular Nonadiabatic Electronic Energy Redistribution (INEER), which is a consequence of the chaotic fluxes of electrons and energy within a molecule.

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Chia, Tze Shyang, e Ching Kheng Quah. "Temperature-induced phase transition of isonicotinamide-malonic acid (2/1) and supramolecular construct analysis of isonicotinamide structures". Zeitschrift für Kristallographie - Crystalline Materials 233, n. 8 (26 luglio 2018): 539–54. http://dx.doi.org/10.1515/zkri-2017-2109.

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Abstract The isonicotinamide-malonic acid (2/1) co-crystal salt (2IN·C3) exhibits a first-order displacive structural phase transition from low-temperature triclinic P1̅ crystal structure to high-temperature monoclinic C2/c crystal structure and vice versa at the transition temperatures of 298 (1) and 295 (1) K, respectively, as determined by variable-temperature SCXRD analysis and DSC measurements. The asymmetric unit of 2IN·C3 comprises three malonic acid molecules and six isonicotinamide molecules at the low-temperature phase, and this is reduced to a half-molecule of malonic acid and an isonicotinamide molecule in the high-temperature phase. The carboxyl and pyridinium H atoms are disordered at both phases. The observed phase transition near room temperature is triggered by the molecular displacement of the isonicotinamide molecule and the syn-anti conformational transformation of the malonic acid molecule with deviation angles of 10.4 and 11.7°, respectively, which induced an energy change of 19.1 kJ mol−1 in the molecular cluster comprising a central isonicotinamide molecule and eight neighboring molecules. However, the total interaction energy of the molecular cluster of a central malonic acid molecule and eight neighboring molecules does not change significantly upon the phase transition. The molecules of isonicotinamide structures except IN·IN+·triazole‒ form zero-dimensional finite arrays or one-dimensional chains as the primary supramolecular construct by carboxyl···pyridyl (−35.9 to −56.7 kJ mol−1) and carboxamide···carboxamide (−53.6 to −68.7 kJ mol−1) or carboxyl···carboxamide (−52.6 to −67.1 kJ mol−1) synthons.

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Du, Xiao Ming, Yong Huang e Er Dong Wu. "Hydrogen - Hydrogen Adsorption Interaction Energy in Zeolites". Advanced Materials Research 187 (febbraio 2011): 797–802. http://dx.doi.org/10.4028/www.scientific.net/amr.187.797.

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A general model based on Ono-Kondo lattice theory for hydrogen adsorption, nearest neighbor interaction energy among adsorbate molecules were derived according to thermodynamic principle. A linear form of the above general model was applied to determine the interaction energies among hydrogen molecules inside adsorption layer from the previous experimental data of hydrogen adsorption on A- and X-type zeolites. The results show that the energies of hydrogen-hydrogen interactions inside the adsorption layer are negative values, indicating that the attractions among the adsorbed hydrogen molecules are prominent in the present work. And the influence of hydrogen molecules outside adsorption layer on the adsorbed hydrogen molecule is not important.

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Day, Graeme. "Insight from energy surfaces: structure prediction by lattice energy exploration". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C28. http://dx.doi.org/10.1107/s2053273314099719.

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A long-standing challenge for the application of computational chemistry in the field of crystallography is the prediction of crystal packing, given no more than the chemical bonding of the molecules being crystallised. Recent years have seen significant progress towards reliable crystal structure prediction methods, even for traditionally challenging systems involving flexible molecules and multi-component solids [1]. These methods are based on global searches of the lattice energy surface: a search is performed to locate all possible packing arrangements, and these structures are ranked by their calculated energy [2]. One aim of this lecture is to provide an overview of advances in methods for crystal structure prediction, focussing on molecular organic crystals, and highlighting strategies that are being explored to extend the reach of these methods to more complex systems. A second aim is to discuss the range applications of crystal structure prediction calculations, which have traditionally included solid form screening, particularly of pharmaceutically active molecules, and structure determination. As energy models become more reliable at correctly ranking the stability order of putative structures, and the timescale required for structure searching decreases, crystal structure prediction has the potential for the discovery of novel molecular materials with targeted properties. Prospects for computer-guided discovery of materials will be discussed.

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Ans, Muhammad, Ahtsham Ayub, Norah Alwadai, Alvina Rasool, Muhammad Zahid, Javed Iqbal e M. S. Al-Buriahi. "Simultaneously enhanced efficiency of eco-friendly structural characterization of the dithienocyclopentacarbazole donor based acceptors with narrow bandgap for high-performance organic solar cells". Journal of Physics D: Applied Physics 55, n. 23 (11 marzo 2022): 235501. http://dx.doi.org/10.1088/1361-6463/ac53c8.

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Abstract In the present age, researchers are trying to overcome the energy crisis and the global demand for energy by developing organic solar cells (OSCs) of higher efficacy. Herein, we have developed five new acceptor molecules with a dithienocyclopentacarbazole donor unit flanked with different electron-withdrawing end-capped acceptor units, named Z1 ((Z)-2-(2-ethylidene-5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile), Z2 ((Z)-1-(dicyanomethylene)-2-ethylidene-3-oxo-2,3-dihydro-1H-indene-5,6-dicarbonitrile), Z3 ((Z)-2-(5-ethylidene-4-oxo-4,5-dihydro-6H-cyclopenta[b]thiophen-6-ylidene)malononitrile), Z4 ((Z)-2-(5-ethylidene-3-fluoro-4-oxo-4,5-dihydro-6H-cyclopenta[b]thiophen-6-ylidene)malononitrile) and Z5 ((Z)-5-((Z)-5-ethylidene-4-oxo-4,5-dihydro-6H-cyclopenta[b]thiophen-6-ylidene)-3-methyl-2-thioxothiazolidin-4-one) to get greater effectiveness and good activity of OSCs, in order for non-renewable resources to be replaced with cost-effective, better-performing OSCs. B3LYP/6-31G(d,p) was used analytically to explore the maximum absorption wavelength ( λ max ), reorganization energy (RE), frontier molecular orbital, transition density matrix, open circuit voltage ( V oc ), density of state, binding energy ( E b ) and dipole moment of the newly developed molecules. Amongst all the newly designed (Z1–Z5) molecules, the Z2 molecule showed the lowest energy gap (2.04 eV) between highest occupied molecular orbital and lowest unoccupied molecular orbital, maximum λ max value in the applied phases i.e. gas (680.74 nm) and solvent (737.0 nm) along with the highest dipole moment values in gas (9.85 Debye) and solvent phase (11.0 Debye), lowest values of reorganization energy, and high charge mobilities. In addition, all the newly designed molecules were found to have the potential for better results in contrast to the molecule R (reference molecule).

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Jumabaev, А., H. Hushvaktov, A. Absanov, A. Norkulov e B. Iltizarov. "Study of diacetyl-water clusters using Raman scattering and theoretical calculations". «Узбекский физический журнал» 24, n. 2 (21 giugno 2022): 110–18. http://dx.doi.org/10.52304/.v24i2.329.

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In this work, the intermolecular interactions of diacetyl and water molecules were studied using the vibration spectrum. The Raman scattering spectra obtained in the range of 500– 2000 cm−1 were analyzed and compared with the results of calculations. For the first time аlso, the charge density distribution and 3D potential energy graphs are examined using simulations for diacetyl molecules. With the increase in the number of molecules at the formation of molecular clusters with the water molecule, the saturation of the intermolecular interaction energy corresponding to a single Н-bond is observed. This corresponds to DA+(Н2O)3 molecular clusters and allows one to conclude that this cluster is stable relative to the others.

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OCHOA, JUAN G. DIAZ. "A MODEL FOR SOLVENT MEDIATED INTERACTIONS BETWEEN MOLECULES AND SURFACES". International Journal of Modern Physics C 20, n. 05 (maggio 2009): 747–59. http://dx.doi.org/10.1142/s0129183109013960.

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This work introduces a novel coarse-grained model representing the dynamics of polar molecules that adsorb on a substrate in the presence of a solvent. The motivation of the model is to avoid the explicit representation of the solvent. Instead, the solvent-mediated interaction is indirectly represented using a fluctuating energy landscape. The dynamics, on which this model is based, are similar to the dynamics in game theory. In particular, the strategy of an agent in a game is similar to the modification of the free energy barrier between the molecule and the substrate induced by other companion molecules. The aim of this method is to show how the interplay between solvents and companion molecules can imply a modification in the adsorption energy of molecules, and how this modification can buffer the adsorption of specific molecules on surfaces. The results, and their implications in the molecular recognition of surfaces, are discussed.

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Ganda-Kesuma, F. S., K. J. Miller, D. Rubenstein, M. J. Bean e J. H. Hellman. "Molecule building, energy optimization and graphics representations of molecules". Journal of Molecular Graphics 9, n. 1 (marzo 1991): 47. http://dx.doi.org/10.1016/0263-7855(91)80050-a.

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Kretić, Danijela S., Vesna B. Medaković e Dušan Ž. Veljković. "How Do Small Differences in Geometries Affect Electrostatic Potentials of High-Energy Molecules? Critical News from Critical Points". Crystals 12, n. 10 (14 ottobre 2022): 1455. http://dx.doi.org/10.3390/cryst12101455.

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The computational design of explosives is becoming very popular since it represents a safe and environmentally friendly way of predicting the properties of these molecules. It is known that positive values of electrostatic potential in the central areas of the molecular surface are a good indicator of the sensitivity of high-energy materials towards detonation. The molecular electrostatic potential is routinely calculated for molecules of explosives using both geometries extracted from crystal structures, and computationally optimized geometries. Here we calculated and compared values of positive electrostatic potential in the centers of five classical high-energy molecules for geometries extracted from different crystal structures and theoretically optimized geometries. Density functional theory calculations performed at M06/cc-PVDZ level showed that there are significant differences in the values of electrostatic potentials in critical points obtained for different geometries of the same high-energy molecules. The study also showed that there was an excellent agreement in the values of electrostatic potentials calculated for optimized geometry of 1,3,5-trinitrobenzene and geometry of this molecule obtained by neutron diffraction experiments. The results of this study could help researchers in the area of the computational development of high-energy molecules to better design their studies and to avoid the production of erroneous results.

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Obayes, Hasan R., Ghadah H. Alwan, Ahmed A. Al-Amiery, Abdul Amir H. Kadhum e Abu Bakar Mohamad. "Thermodynamic and Theoretical Study of the Preparation of New Buckyballs from Corannulene, Coronene, and Circulene". Journal of Nanomaterials 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/451920.

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We applied density functional theory (DFT) to study three polycyclic aromatic compounds (PAHs), corannulene, coronene, and circulene, for the preparation of twelve new buckyballs with molecular dimensions of less than a nanometer. The results showed that the corannulene molecule is bowl-shaped, the coronene molecule is planar, and the circulene molecule has a unique saddle-shaped structure. Cyclic polymerization of the three molecules can be used to prepare new buckyballs, and this process produces hydrogen molecules. The most symmetric buckyball is also the most stable based on the values of the HOMO energy levels and has the most efficient gap energy, making it potentially useful for solar cell applications.

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Putthikorn, Sasipim, Thien Tran-Duc, Ngamta Thamwattana, James M. Hill e Duangkamon Baowan. "Interacting Ru(bpy) 3 2 + Dye Molecules and TiO2 Semiconductor in Dye-Sensitized Solar Cells". Mathematics 8, n. 5 (22 maggio 2020): 841. http://dx.doi.org/10.3390/math8050841.

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Solar energy is an alternative source of energy that can be used to replace fossil fuels. Various types of solar cells have been developed to harvest this seemingly endless supply of energy, leading to the construction of solar cell devices, such as dye-sensitized solar cells. An important factor that affects energy conversion efficiency of dye-sensitized solar cells is the distribution of dye molecules within the porous semiconductor (TiO 2 ). In this paper, we formulate a continuum model for the interaction between the dye molecule Tris(2,2 ′ -bipyridyl)ruthenium(II) (Ru(bpy) 3 2 + ) and titanium dioxide (TiO 2 ) semiconductor. We obtain the equilibrium position at the minimum energy position between the dye molecules and between the dye and TiO 2 nanoporous structure. Our main outcome is an analytical expression for the energy of the two molecules as a function of their sizes. We also show that the interaction energy obtained using the continuum model is in close agreement with molecular dynamics simulations.

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Danielson, J. R., S. Ghosh e C. M. Surko. "Influence of geometry on positron binding to molecules". Journal of Physics B: Atomic, Molecular and Optical Physics 54, n. 22 (17 novembre 2021): 225201. http://dx.doi.org/10.1088/1361-6455/ac3e78.

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Abstract Annihilation studies have established that positrons bind to most molecules. They also provide measurements of the positron-molecule binding energies, which are found to vary widely and depend upon molecular size and composition. Trends of binding energy with global parameters such as molecular polarizability and dipole moment have been discussed previously. In this paper, the dependence of binding energy on molecular geometry is investigated by studying resonant positron annihilation on selected pairs of isomers. It is found that molecular geometry can play a significant role in determining the binding energies even for isomers with very similar polarizabilities and dipole moments. The possible origins of this dependence are discussed.

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Rangel, E., L. F. Magana, L. E. Sansores e G. J. Vázquez. "Generation of hydrogen peroxide on a pyridine-like nitrogen-nickel doped graphene surface". MRS Proceedings 1451 (2012): 69–74. http://dx.doi.org/10.1557/opl.2012.1335.

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ABSTRACTDensity functional theory and molecular dynamics were used to study the generation of hydrogen peroxide around a nickel atom anchored on a pyridine-like nitrogen-doped graphene (PNG) layer. First, we found that two hydrogen molecules are adsorbed around the nickel atom, with adsorption energy 0.95 eV/molecule. Then we studied the interaction of oxygen molecules with this system at atmospheric pressure and 300 K. It is found that two hydrogen peroxide molecules are formed. However, at 700 K, one hydrogen peroxide molecule, and one water molecule are desorbed. One oxygen atom stays bound to the nickel atom.

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MAITI, SANTANU K., e S. N. KARMAKAR. "QUANTUM TRANSPORT THROUGH HETEROCYCLIC MOLECULES". International Journal of Modern Physics B 23, n. 02 (20 gennaio 2009): 177–87. http://dx.doi.org/10.1142/s021797920904970x.

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We explore electron transport properties in molecular wires made of heterocyclic molecules (pyrrole, furan and thiophene) by using the Green's function technique. Parametric calculations are given based on the tight-binding model to describe the electron transport in these wires. It is observed that the transport properties are significantly influenced by (a) the heteroatoms in the heterocyclic molecules and (b) the molecule-to-electrodes coupling strength. Conductance (g) shows sharp resonance peaks associated with the molecular energy levels in the limit of weak molecular coupling, while they get broadened in the strong molecular coupling limit. These resonances get shifted with the change of the heteroatoms in these heterocyclic molecules. All the essential features of the electron transfer through these molecular wires become much more clearly visible from the study of our current-voltage (I-V) characteristics, and they provide several key information in the study of molecular transport.

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Alshehri, Mansoor H. "Continuous Approximation for Interaction Energy Transfer of DNA through Lipid Bilayers". Discrete Dynamics in Nature and Society 2018 (1 novembre 2018): 1–10. http://dx.doi.org/10.1155/2018/7017416.

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In this study the interaction energies for single-stranded DNA and double-stranded DNA molecules with a lipid bilayer are investigated. The 6-12 Lennard-Jones potential and continuous approximation are used to derive analytical expressions for these interaction energies. Assuming that there is a circular gap in the lipid bilayer, we determine the relationship of the molecular interaction energy, including the circular gap radius and the perpendicular distance of the single-stranded DNA and double-stranded DNA molecules from the gap. For both single-stranded and double-stranded DNA molecules, the relationship between the minimum energy location and the hole radius b is calculated; in the case of the double-stranded DNA molecule, we assume that the helical phase angle ϕ is equal to π. By minimizing the total interaction energies, the results demonstrate that the single-stranded DNA and double-stranded DNA molecules move through a lipid bilayer when the gap radius b> 10 Å and b> 13.8 Å, respectively. The results present in this project can be leveraged to understand the interactions between cell-penetrating peptides and biomembranes, which may improve gene and drug delivery.

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ALTUN, Ali, e Guventurk UGURLU. "Investigation of Conformational Analysis of (m-Carbamoylphenyl) Boronic Acid Molecules by Theoretical Methods". Eurasia Proceedings of Science Technology Engineering and Mathematics 20 (21 dicembre 2022): 21–29. http://dx.doi.org/10.55549/epstem.1220256.

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In this study, the structural parameters, the electronic energy, the dipole moment (μ), the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy, the polarizability (α), hyperpolarizability (β) and vibrational frequency of (3-Carbamoylphenyl) boronic acid were calculated at Density Functional Theory (DFT) with B3LYP (Becke 3 Parameter Lee-Yang-Parr) model using the 6-311+(2d,p) basis set in gas phase. Also, using the EHOMO and ELUMO energy values of the molecule, the energy gap (Eg = ELUMO -EHOMO), electronegativity (χ), chemical potential (Pi), chemical hardness (η), softness (σ), ionization energy (I), electron affinity (A), electronic chemical potential (µ), global softness (S) values were calculated according to the literature. Equilibrium state (ground state) energy gap value of the molecule were calculated as 5.59 eV. The dipole moment value of the molecule was calculated as 3.41 Debye by the DFT/B3LYP/6-311+G(2d,p) method. The obtained vibrational wave numbers were scaled with appropriate scale factors and the assigning of these vibrational wavenumbers was made according to the potential energy distribution (PED) using the VEDA 4f program. The approximate geometry of the molecules in three dimensions was drawn in the Gauss View 5.0 molecular imaging program, and all theoretical calculations were used with the Gaussian 09W package program.

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MOHAJERI, AFSHAN, e MOJTABA ALIPOUR. "INFORMATION ENERGY AS AN ELECTRON CORRELATION MEASURE IN ATOMIC AND MOLECULAR SYSTEMS". International Journal of Quantum Information 07, n. 04 (giugno 2009): 801–9. http://dx.doi.org/10.1142/s0219749909005365.

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The information energy is proposed as a possible measure for electron correlation energy in atoms and molecules. For neutral atoms and their cations, we proposed an expression for correlation energy with explicit dependence on the information energy and atomic number. The obtained correlation energies have been used to compute the first ionization potentials of the ground state of the main group elements from hydrogen through krypton. It is shown that the information energy of a molecule can be well-estimated by use of the information energies of its constituent atoms. On the basis of the molecular information energy and number of electrons in the molecule, a simple model has been proposed for evaluation of molecular correlation energy.

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Ислам гызы Велиева, Лала, e Фарида Махир гызы Мамедова. "Spatial structure of the met callatostatin neuropeptide". NATURE AND SCIENCE 03, n. 01 (5 marzo 2021): 59–67. http://dx.doi.org/10.36719/2707-1146/06/59-67.

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In work by the method of molecular mechanics in approximation of atom-atom potential functions is studied the spatial structure and conformational properties of the molecules from allatostatin family, got the name of Met-callatostatin. The researches were based on minimizing of the energy of intramolecular interactions (non-bonded, electrostatic, torsion) in the vicinity of the internal rotation angles corresponding to all combinations of stable conformations of monopeptide residues forming a molecule. There determined ten energetically stable conformations of molecules, implemented under the conditions of implicitly given aqueous environment, the relative conformational energy of which varies in the range of 0-10 kcal / mol. It was shown that the system of hydrogen bonds, despite a small contribution to the total energy of the molecule is essential for the preservation of a stable structure and restriction of Met-callatostatin. Key words: neuropeptides, structure, conformational analysis, peptides, by molecular mechanics

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Mörschel, Philipp, e Martin U. Schmidt. "Prediction of molecular crystal structures by a crystallographic QM/MM model with full space-group symmetry". Acta Crystallographica Section A Foundations and Advances 71, n. 1 (1 gennaio 2015): 26–35. http://dx.doi.org/10.1107/s2053273314018907.

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A crystallographic quantum-mechanical/molecular-mechanical model (c-QM/MM model) with full space-group symmetry has been developed for molecular crystals. The lattice energy was calculated by quantum-mechanical methods for short-range interactions and force-field methods for long-range interactions. The quantum-mechanical calculations covered the interactions within the molecule and the interactions of a reference molecule with each of the surrounding 12–15 molecules. The interactions with all other molecules were treated by force-field methods. In each optimization step the energies in the QM and MM shells were calculated separately as single-point energies; after adding both energy contributions, the crystal structure (including the lattice parameters) was optimized accordingly. The space-group symmetry was maintained throughout. Crystal structures with more than one molecule per asymmetric unit,e.g.structures withZ′ = 2, hydrates and solvates, have been optimized as well. Test calculations with different quantum-mechanical methods on nine small organic molecules revealed that the density functional theory methods with dispersion correction using the B97-D functional with 6-31G* basis set in combination with the DREIDING force field reproduced the experimental crystal structures with good accuracy. Subsequently the c-QM/MM method was applied to nine compounds from the CCDC blind tests resulting in good energy rankings and excellent geometric accuracies.

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Francisco, E., A. Martín Pendás e M. A. Blanco. "A Molecular Energy Decomposition Scheme for Atoms in Molecules". Journal of Chemical Theory and Computation 2, n. 1 (2 dicembre 2005): 90–102. http://dx.doi.org/10.1021/ct0502209.

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Awad, Ibrahim E., e Raymond A. Poirier. "Atoms and bonds in molecules: Molecular radial energy densities". Computational and Theoretical Chemistry 1153 (aprile 2019): 44–53. http://dx.doi.org/10.1016/j.comptc.2019.03.002.

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Suzuki, Yoshi-Ichi. "Structure of molecular energy levels of homonuclear diatomic molecules". International Journal of Quantum Chemistry 72, n. 6 (1999): 597–604. http://dx.doi.org/10.1002/(sici)1097-461x(1999)72:6<597::aid-qua6>3.0.co;2-5.

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Zhang, Yong, Qiuyun Wang, Anmin Chen e Xun Gao. "Effect of laser pulse energy on atomic lines and molecular bands in femtosecond LIBS of aluminum". Laser Physics 33, n. 7 (18 maggio 2023): 076003. http://dx.doi.org/10.1088/1555-6611/acd4ad.

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Abstract This study explored the characteristics of atomic and molecular emissions in Al plasmas generated by femtosecond lasers. The influence of laser pulse energy on Al atoms and AlO molecules time-integrated spectra was examined. As laser pulse energy increased, the intensity of Al atoms increased, while the emission of AlO molecules first increased and then remained unchanged. Secondly, the vibration temperature of AlO was determined and found to result in strong emission at a low temperature. Finally, the influence of laser pulse energy on the time-resolved spectra of Al atom and AlO molecule was explored, finding consistency with the time-integrated emission. These results indicate that the Al atom and AlO molecule have different sensitivities to femtosecond laser pulse energy. This research enriches our knowledge of femtosecond laser-plasma interactions and has potential applications in material processing and spectroscopic analysis.

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Zou, Yan, Yue Wu, Hang Yang, Yingying Dong, Chaohua Cui e Yongfang Li. "The effect of alkylthio side chains in oligothiophene-based donor materials for organic solar cells". Molecular Systems Design & Engineering 3, n. 1 (2018): 131–41. http://dx.doi.org/10.1039/c7me00075h.

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The engineering of alkylthio side chains in the molecular conjugated backbone of small molecules is in favor of achieving a linear molecular backbone conformation, slightly red-shifting the absorption spectrum, and down-shifting the HOMO energy level of the resulting molecule.

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37

Tyutyulkov, N., F. Dietz e G. Olbrich. "On alternant molecules with identical energy spectra: Isospectral molecules". International Journal of Quantum Chemistry 62, n. 2 (1997): 167–69. http://dx.doi.org/10.1002/(sici)1097-461x(1997)62:2<167::aid-qua4>3.0.co;2-u.

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38

Abdul Rahman Rashid Hammood, Abdul Hakim shakkoor Mohammed e Nadim Khalid Hassan. "STUDYING AND CALCULATION OF THE POTENTIAL ENERGY FOR TWO OF MOLECULES [TRIMETHYL GALLIUM AND TRIETHYL GALLIUM,] BY SEMI EMPIRICAL PROGRAMS". Tikrit Journal of Pure Science 22, n. 3 (27 gennaio 2023): 146–55. http://dx.doi.org/10.25130/tjps.v22i3.724.

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In this research, the potential energy and vibration frequencies for two of an non-liner molecules [ (C3H9Ga) and (C6H15Ga)] have been studied and calculated by using the semi-empirical theoretical programs in method (MNDO/PM3) where the geometric space shape of two molecules has been calculated by using initial and final matrices that include bonds length, the angle between bonds, dihedral angles and the charge of each atom in the two molecules, which have been drawing a curved of potential energy per molecule where the drawing was adopted to change the length of the bond (Ga-C) in the each molecule compared to what is obtained from the values of energy and it was total energy calculate for each molecule at equilibrium distance was (-553.044 eV) at equilibrium distance (1.8327 ) and (-1003.53726 eV) at equilibrium distance (1.8344 ) for the two molecules, respectively, and from the carve of the potential energy was the spectroscopy dissociation energy per molecule account it was equal to (4.508 eV) and (4.70991 eV) respectively .

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Sunarmi, Nani. "SIMULASI PENYELESAIAN TINGKAT ENERGI SISTEM MOLEKUL DALAM PENGARUH POTENSIAL KRATZER DENGAN METODE PARAMETRIK NIKIFOROV-UVAROV". ORBITA: Jurnal Kajian, Inovasi dan Aplikasi Pendidikan Fisika 8, n. 2 (18 novembre 2022): 383. http://dx.doi.org/10.31764/orbita.v8i2.11452.

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ABSTRAKTelah dilakukan kajian terhadap potensial Kratzer pada sistem molekul dengan menggunakan metode Parametrik Nikiforov-Uvarov. Penelitian bermaksud mendapatkan persamaan tingkat energi sistem dalam pengaruh potensial Kratzer dan melakukan simulasi terhadap persamaan tingkat energi tersebut untuk molekul oksigen, iodin, karbon monoksida, nitrogen monoksida. Penyelesaian tingkat energi sistem diperoleh dengan memisahkan persamaan Schrodinger sistem partikel menjadi 3 bagian yakni radial, zenithal dan azimuthal. Penyelesaian tingkat energi diperoleh dengan meninjau persamaan Schrodinger sistem partikel bagian radial. Penyelesaian persamaan tingkat energi dilakukan dengan menerapkan metode Parametrik Nikiforov-Uvarov. Penyelesaian terhadap persamaan Schrodinger sistem partikel bagian radial dilakukan dengan mereduksi persamaan menjadi persamaan diferensial tipe hipergeometri. Komputasi numerik dan simulasi grafik tingkat energi dilakukan dengan menggunakan Matlab. Berdasarkan hasil penelitian diperoleh penyelesaian persamaan tingkat energi bergantung parameter energi disosiasi, panjang ikatan kesetimbangan, bilangan kuantum serta massa molekul. Molekul iodin memiliki tingkat energi paling rendah dibandingkan molekul oksigen, karbon monoksida, nitrogen monoksida. Kata kunci: tingkat energi; potensial kratzer; metode parametrik nikiforov-uvarov. ABSTRACTA study of the Kratzer potential in molecular systems has been carried out using the Nikiforov-Uvarov Parametric method. The research aims to obtain the energy level equations of the system under the influence of the Kratzer potential and carry out simulations of these energy level equations for oxygen, iodine, carbon monoxide, nitrogen monoxide molecules. The solution for the energy level of the system is obtained by separating the Schrodinger equation of the particle system into 3 parts, namely radial, zenithal and azimuthal. The solution for energy levels is obtained by considering the Schrodinger equation of the radial section particle system. Solving the energy level equation is done by applying the Nikiforov-Uvarov Parametric method. The solution to the Schrodinger equation of the radial section particle system is carried out by reducing the equation to a hypergeometric type differential equation. Numerical computations and graphical simulations of energy levels are carried out using Matlab. Based on the research results, it was found that the solution to the energy level equation depends on the parameters of dissociation energy, equilibrium bond length, quantum number and molecular mass. Iodine molecule has the lowest energy level compared to oxygen molecules, carbon monoxide, nitrogen monoxide. Keywords: energy level; kratzer potential; nikiforov-uvarov parametric method.

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Dejanova, B., S. Petrovska, J. Pluncevic Gligoroska, S. Mancevska, B. Spirkovska Vangelovska e M. Nestorova Brazanska. "ENERGY REGULATION BY DIFFERENT MOLECULES". Research in Physical Education, Sport and Health 11, n. 1 (2022): 25–31. http://dx.doi.org/10.46733/pesh22111025d.

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41

Ho, Y. K. "Binding energy of positronium molecules". Physical Review A 33, n. 5 (1 maggio 1986): 3584–87. http://dx.doi.org/10.1103/physreva.33.3584.

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42

Maksimović, G., I. V. Puzynin, T. A. Strizh e F. R. Vukajlović. "Energy levels of excitonic molecules". Physical Review B 38, n. 5 (15 agosto 1988): 3351–53. http://dx.doi.org/10.1103/physrevb.38.3351.

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Kaur, Sarvpreet, e C. G. Mahajan. "Dissociation energy of diatomic molecules". Pramana 50, n. 5 (maggio 1998): 397–403. http://dx.doi.org/10.1007/bf02847369.

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44

Wang, Zengyao, Hao Wu, Qingyun Wu, Yi-Ming Zhao e Lei Shen. "Magnetic ε-Phosphorene for Sensing Greenhouse Gas Molecules". Molecules 28, n. 14 (14 luglio 2023): 5402. http://dx.doi.org/10.3390/molecules28145402.

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It is critical for gas sensors that sense greenhouse gas molecules to have both good sensitivity and selectivity for water molecules in the ambient environment. Here, we study the charge transfer, IV curves, and electric field tuning of vanadium-doped monolayer ϵ-phosphorene as a sensor for NO, NO2, and H2O gas molecules via first-principle and transport calculations. We find that the paramagnetic toxic molecules of NO and NO2 have a high adsorption energy on V-ϵ-phosphorene, which originates from a large amount of charge transfer driven by the hybridisation of the localised spin states of the host with the molecular frontier orbital. Using the non-equilibrium Green’s function, we investigate the IV responses with respect to the adsorption of different molecules to study the performance of gas molecule sensors. Our IV curves show a larger amount of changes in resistance of the paramagnetic NO and NO2 than nonmagnetic H2O gas molecules, suggesting both sensitivity and selectivity. Moreover, our calculations show that an applied external electric field (gate voltage) can effectively tune the amount of charge transfer. More charge transfer makes the sensor more sensitive to the molecule, while less charge transfer can reduce the adsorption energy and remove the adsorbed molecules, allowing for the repeated use of the sensor.

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Borodin, Vladislav, Mikhail Bubenchikov, Alexey Bubenchikov, Dmitriy Mamontov, Sergey Azheev e Alexandr Azheev. "Study of the Unstable Rotational Dynamics of a Tor-Fullerene Molecular System". Crystals 13, n. 2 (20 gennaio 2023): 181. http://dx.doi.org/10.3390/cryst13020181.

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This work is devoted to modeling the dynamics of large molecules. The key issue in modeling the dynamics of real molecular systems is to correctly represent the temperature of the system using the available theoretical tools. In most works on molecular dynamics, vibrations of atoms inside a molecule are modeled with enviable persistence, which has nothing to do with physical temperature. These vibrations represent the energy internal to the molecule. Therefore, it should not be present in problems in the dynamics of inert molecular systems. In this work, by means of classical mechanics, it is shown that the simplest system containing only three molecular bodies, due to multiple acts of pair interactions of these bodies, reproduces the temperature even in an extremely complex unstable motion of the system. However, at the same time, it is necessary to separate the stochastic part of the movement from the deterministic one. Calculations also show that translational fluctuations in the motion of molecules make the greatest contribution to temperature. The contribution of rotational energy to the total energy of fluctuation motions is small. It follows from these results that the thermal state of the system is determined only by the translational temperature. The latter, in turn, opens up possibilities for a simplified description of many complex systems composed of carbon molecules such as fullerenes and nanotori.

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Tourleigh, Ye V., K. V. Shaitan e N. K. Balabaev. "Diffusion of Molecules at the Interface of Water-Membrane Structures". Defect and Diffusion Forum 261-262 (gennaio 2007): 109–26. http://dx.doi.org/10.4028/www.scientific.net/ddf.261-262.109.

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The distributions and transfer energies of several molecules and atomic groups between water and a structured hydrophobic phase were calculated by the molecular dynamics method. The coefficients of oxygen diffusion in a tetradecane membrane were estimated. The transfer energy of charged atomic groups was found to correlate with changes in the Born solvation energy. The contributions of atoms to the transfer energy of functional groups were shown to be non-additive. The steered dynamics method for estimating the kinetic parameters of the penetration of molecules through interphase boundaries was developed. Heterogeneous microviscosity of a membrane was calculated for a hydrated l-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine bilayer. Effects of the chemical properties of penetrant molecule on its translocation through the membrane were studied.

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Jose, Jeeno, Alon Zamir e Tamar Stein. "Molecular dynamics reveals formation path of benzonitrile and other molecules in conditions relevant to the interstellar medium". Proceedings of the National Academy of Sciences 118, n. 19 (3 maggio 2021): e2101371118. http://dx.doi.org/10.1073/pnas.2101371118.

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Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are believed to be widespread in different areas of the interstellar medium. However, the astronomical detection of specific aromatic molecules is extremely challenging. As a result, only a few aromatic molecules have been identified, and very little is known about how they are formed in different areas of the interstellar medium. Recently, McGuire et al. [Science 359, 202–205 (2018)] detected the simple aromatic molecule benzonitrile in Taurus Molecular Cloud-1. Although benzonitrile has been observed, the molecular mechanism for its formation is still unknown. In this study, we use quantum chemistry and ab initio molecular dynamics to model ionization processes of van der Waals clusters containing cyanoacetylene and acetylene molecules. We demonstrate computationally that the clusters' ionization leads to molecular formation. For pure cyanoacetylene clusters, we observe bond formation among two and three monomer units, whereas in mixed clusters, bond formation can also occur in up to four units. We show that the large amount of energy available to the system after ionization can lead to barrier crossing and the formation of complex molecules. Our study reveals the rich chemistry that is observed upon ionization of the clusters, with a wide variety of molecules being formed. Benzonitrile is among the observed molecules, and we study the potential energy path for its formation. These results also offer insights that can guide astronomers in their search for aromatic molecules in the interstellar medium.

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Levitt, Malcolm H. "Spectroscopy of light-molecule endofullerenes". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, n. 1998 (13 settembre 2013): 20120429. http://dx.doi.org/10.1098/rsta.2012.0429.

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Molecular endofullerenes are supramolecular systems consisting of fullerene cages encapsulating small molecules. Although most early examples consist of encapsulated metal clusters, recently developed synthetic routes have provided endofullerenes with non-metallic guest molecules in high purity and macroscopic quantities. The encapsulated light molecule behaves as a confined quantum rotor, displaying rotational quantization as well as translational quantization, and a rich coupling between the translational and rotational degrees of freedom. Furthermore, many encapsulated molecules display spin isomerism. Spectroscopies such as inelastic neutron scattering, nuclear magnetic resonance and infrared spectroscopy may be used to obtain information on the quantized energy level structure and spin isomerism of the guest molecules. It is also possible to study the influence of the guest molecules on the cages, and to explore the communication between the guest molecules and the molecular environment outside the cage.

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Yang, Huan, Jin Cao, Zhen Su, Jun Rui, Bo Zhao e Jian-Wei Pan. "Creation of an ultracold gas of triatomic molecules from an atom–diatomic molecule mixture". Science 378, n. 6623 (2 dicembre 2022): 1009–13. http://dx.doi.org/10.1126/science.ade6307.

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In recent years, there has been notable progress in the preparation and control of ultracold gases of diatomic molecules. The next experimental challenge is the production of ultracold polyatomic molecular gases. Here, we report the creation of an ultracold gas of 23 Na 40 K 2 triatomic molecules from a mixture of ground-state sodium-23–potassium-40 ( 23 Na 40 K) molecules and potassium-40 ( 40 K) atoms. The triatomic molecules were created by adiabatic magneto-association through an atom–diatomic molecule Feshbach resonance. We obtained clear evidence for the creation of triatomic molecules by directly detecting them using radio-frequency dissociation. Approximately 4000 triatomic molecules with a high-peak phase-space density of 0.05 could be created. The ultracold triatomic molecules can serve as a launchpad to probe the three-body potential energy surface and may be used to prepare quantum degenerate triatomic molecular gases.

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Yuan, Qiang, e Xi-Wen Hou. "Entropy, energy, and entanglement of localized states in bent triatomic molecules". International Journal of Modern Physics B 31, n. 12 (10 maggio 2017): 1750088. http://dx.doi.org/10.1142/s0217979217500886.

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The dynamics of quantum entropy, energy, and entanglement is studied for various initial states in an important spectroscopic Hamiltonian of bent triatomic molecules H2O, D2O, and H2S. The total quantum correlation is quantified in terms of the mutual information and the entanglement by the concurrence borrowed from the theory of quantum information. The Pauli entropy and the intramolecular energy usually used in the theory of molecules are calculated to establish a possible relationship between both theories. Sections of two quantities among these four quantities are introduced to visualize such relationship. Analytic and numerical simulations demonstrate that if an initial state is taken to be the stretch- or the bend-vibrationally localized state, the mutual information, the Pauli entropy, and the concurrence are dominant-positively correlated while they are dominantly anti-correlated with the interacting energy among three anharmonic vibrational modes. In particular, such correlation is more distinct for the localized state with high excitations in the bending mode. The nice quasi-periodicity of those quantities in D2O molecule reveals that this molecule prepared in the localized state in the stretching or the bending mode can be more appreciated for molecular quantum computation. However, the dynamical correlations of those quantities behave irregularly for the dislocalized states. Moreover, the hierarchy of the mutual information and the Pauli entropy is explicitly proved. Quantum entropy and energy in every vibrational mode are investigated. Thereby, the relation between bipartite and tripartite entanglements is discussed as well. Those are useful for the understanding of quantum correlations in high-dimensional states in polyatomic molecules from quantum information and intramolecular dynamics.

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