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Sliter R, Hyeon-Deuk K, Vilesov AF. Phase Separation in Cold Para-H_{2} D_{2} Clusters. PHYSICAL REVIEW LETTERS 2024; 132:206001. [PMID: 38829090 DOI: 10.1103/physrevlett.132.206001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/11/2024] [Indexed: 06/05/2024]
Abstract
Low temperature phase separation in mixtures of ^{3}He and ^{4}He isotopes is a unique property of quantum fluids. Hydrogen has long been considered as another potential quantum liquid and has been predicted to be superfluid at T≤1 K, well below freezing temperature of ≈14 K. Phase separation has also been predicted in mixtures of para-H_{2} and D_{2} at temperatures ≤3 K. To defer the freezing, we produced clusters containing para-H_{2} and D_{2} at an estimated temperature of ≈2 K whose state was studied by vibrational Raman spectroscopy. The results indicate that the clusters are liquid and show the phase separation of the isotopes. The phase separation is further corroborated by the quantum molecular dynamics simulation.
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Affiliation(s)
- Russell Sliter
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
| | - Andrey F Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
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2
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Ando K. Potential energy surfaces for electron dynamics from a model of localized Gaussian wave packets with valence-bond spin-coupling: High-harmonic generation spectra from H and He atoms. Chem Phys 2023. [DOI: 10.1016/j.chemphys.2023.111883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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3
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Chang IY, Yamaoka S, Hyeon-Deuk K. Anomalously supercooled H 2-D 2 mixtures flowing inside a carbon nano tube. Phys Chem Chem Phys 2023; 25:3232-3239. [PMID: 36625370 DOI: 10.1039/d2cp04509e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
H2 and D2 molecules condensed in a carbon nano tube (CNT) and their nonequilibrium flow through nano pores offer a key test to reveal mass molecular transport and separation of purely isotopic molecules that possess the same electronic potential but a two-times difference in mass inducing differently enhanced nuclear quantum effects (NQEs) such as nuclear delocalization and zero-point energy. Taking advantage of the non-empirical quantum molecular dynamics method developed for condensed H2-D2 molecules that can describe various kinds of condensed phases and thermodynamic states including uneven density and a shear flow, we investigated condensed isotopic H2-D2 mixtures flowing inside nanoscale adsorbable CNTs. We found that, in any mixture, the more delocalized H2 molecules are more supercooled than the less delocalized D2 molecules in a two-dimensional liquid film adsorbed around the CNT well, and that the stronger supercooling of the H2 molecules than the D2 molecules in an equilibrium state becomes more enhanced under the nonequilibrium flow due to the isotope-dependent flow-induced condensation, demonstrating the anomalous condensed-phase quantum sieving under the nonequilibrium flow and its dependence on the mixing ratio and temperature. The differently enhanced NQEs of the purely isotopic molecules essentially influence the condensed adsorption and their flows occurring in the nanoscale CNT, which should be distinguished from a dilute gas adsorption. The predicted properties and obtained physical insights in this paper will help in experimentally controlling condensed H2-D2 mixtures, and open a new strategy and innovative design of nanoporous materials for adsorptive separation of condensed-phase mixtures under a nonequilibrium flow not of a dilute gas mixture in an equilibrium state.
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Affiliation(s)
- I-Ya Chang
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.
| | - Shutaro Yamaoka
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.
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4
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Real-time hydrogen molecular dynamics satisfying the nuclear spin statistics of a quantum rotor. Commun Chem 2022; 5:168. [PMID: 36697851 PMCID: PMC9814564 DOI: 10.1038/s42004-022-00788-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 11/24/2022] [Indexed: 12/07/2022] Open
Abstract
Apparent presence of the nuclear-spin species of a hydrogen molecule, para-hydrogen and ortho-hydrogen, associated with the quantum rotation is a manifestation of the nuclear quantum nature of hydrogen, governing not only molecular structures but also physical and chemical properties of hydrogen molecules. It has been a great challenge to observe and calculate real-time dynamics of such molecularized fermions. Here, we developed the non-empirical quantum molecular dynamics method that enables real-time molecular dynamics simulations of hydrogen molecules satisfying the nuclear spin statistics of the quantum rotor. While reproducing the species-dependent quantum rotational energy, population ratio, specific heat, and H-H bond length and frequency, we found that their translational, orientational and vibrational dynamics becomes accelerated with the higher rotational excitation, concluding that the nuclear quantum rotation stemmed from the nuclear spin statistics can induce various kinds of dynamics and reactions intrinsic to each hydrogen species.
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5
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Yamaoka S, Chang IY, Hyeon-Deuk K. Flow-Induced Autonomic Ordering of Hydrogen Molecules under a Non-Equilibrium Flow. J Phys Chem Lett 2022; 13:3579-3585. [PMID: 35426681 DOI: 10.1021/acs.jpclett.2c00914] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A non-equilibrium molecular flow through a carbon nanotube (CNT) serves as a key system for revealing molecular transport and establishing nanofluidics. It has been challenging to simulate a non-equilibrium flow of hydrogen molecules exhibiting strong nuclear quantumness. Taking advantage of the quantum molecular dynamics method that can calculate real-time trajectories of hydrogen molecules even under a non-equilibrium flow, we found that the non-equilibrium flow makes hydrogen molecules more condensed and accelerates their adsorption near a CNT surface, letting the molecules flow more smoothly by propagating velocity momenta more efficiently along the CNT axis and by suppressing transverse molecular dynamics on the CNT cross section. Such flow-induced autonomic ordering indicates the importance of monitoring and investigating dynamics and adsorption of hydrogen molecules under a non-equilibrium circumstance as well as in a quiet equilibrium state, opening a new strategy for efficient hydrogen liquefaction and storage.
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Affiliation(s)
- Shutaro Yamaoka
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
| | - I-Ya Chang
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
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6
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Yamaoka S, Hyeon-Deuk K. Distinct molecular dynamics dividing liquid-like and gas-like supercritical hydrogens. Phys Chem Chem Phys 2021; 23:22110-22118. [PMID: 34580684 DOI: 10.1039/d1cp02650j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Understanding how a supercritical fluid is related to normal liquid and gas and separating it into liquid-like and gas-like regions are of fundamental and practical importance. Despite the usefulness of hydrogen storage, molecular dynamics images on supercritical hydrogens exhibiting strong nuclear quantum effects are scarce. Taking advantage of the non-empirical ab initio molecular dynamics method for hydrogen molecules, we found that, while radial distribution functions and diffusion show a monotonic change along the density, van Hove time correlation functions and intramolecular properties such as bond length and vibrational frequency exhibit the anomalous order crossing the Widom line. By demonstrating that the anomalous order stemmed from the largest deviations between liquid-like and gas-like solvations formed around the Widom line, we concluded that this supercritical fluid is a mixture of liquid and gas possessing heterogeneity. The obtained physical insights can be an index to monitor the supercriticality and to identify distinct liquid-like and gas-like supercritical fluids.
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Affiliation(s)
- Shutaro Yamaoka
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan.
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7
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Yamaoka S, Hyeon-Deuk K. Decelerated Liquid Dynamics Induced by Component-Dependent Supercooling in Hydrogen and Deuterium Quantum Mixtures. J Phys Chem Lett 2020; 11:4186-4192. [PMID: 32375000 DOI: 10.1021/acs.jpclett.0c00801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Isotopic mixtures of p-H2 and o-D2 molecules have been an attractive binary system because they include two kinds of purely isotopic molecules which possess the same electronic potential but the twice different mass inducing differently pronounced nuclear quantum effects (NQEs). Accessing details of structures and dynamics in such quantum mixtures combining complex molecular dynamics with NQEs of different strengths remains a challenging problem. Taking advantage of the nonempirical molecular dynamics method which describes p-H2 and o-D2 molecules, we found that the liquid dynamics slows down at a specific mixing ratio, which can be connected to the observed anomalous slowdown of crystallization in the quantum mixtures. We attributed the decelerated dynamics to the component-dependent supercooling of p-H2 taking place in the mixtures, demonstrating that there is an optimal mixing ratio to hinder crystallization. The obtained physical insights will help in experimentally controlling and achieving unknown quantum mixtures including superfluid.
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Affiliation(s)
- Shutaro Yamaoka
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
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Ando K. Single-electron quantum dynamics in high-harmonic generation spectrum from LiH molecule: Analysis of potential energy surfaces for electrons constructed from a model of localized Gaussian wave packets with valence-bond spin-coupling. J Chem Phys 2020; 152:084306. [DOI: 10.1063/1.5139079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Koji Ando
- Department of Information and Sciences, Tokyo Woman’s Christian University, 2-6-1 Zenpukuji, Suginami-ku, Tokyo 167-8585, Japan
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9
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Colognesi D, Bafile U, Celli M, Neumann M, Guarini E, Le MD. Hydrogen self-dynamics in diluted liquid mixtures with neon: An inelastic neutron scattering study. Phys Rev E 2019; 99:012138. [PMID: 30780317 DOI: 10.1103/physreve.99.012138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Indexed: 11/07/2022]
Abstract
We have measured the dynamic structure factor of liquid neon-hydrogen mixtures (T=30.1 K) at two different H_{2} concentration levels (namely, 3.4% and 10%) making use of inelastic neutron scattering. This system has been selected since the presence of heavy Ne atoms strongly influences the self-dynamics of the H_{2} centers of mass via the formation of short-lived cages, which act both on the vibrational and the diffusive parts of the single-particle motion. After operating a standard data reduction and the subtraction of the Ne signal, experimental neutron spectra were analyzed through a generalization of the Young and Koppel model, and the H_{2} center-of-mass self-dynamic structure factor was finally extracted for the two liquid samples. Important physical quantities (namely, single-particle mean kinetic energy and self-diffusion coefficient) were estimated from the experimental data and then compared with quantum dynamical calculations, which also provided simulations of the velocity autocorrelation functions for Ne atoms and H_{2} centers of mass. The latter estimates, in the framework of the well-known Gaussian approximation, were used to simulate the H_{2} center-of-mass self-dynamic structure factor in the same kinematic range and thermodynamic conditions of the neutron scattering one. The comparison between measured and calculated spectra turned out to be qualitatively good, but some discrepancies, especially in the low-frequency part, seem to reinforce the idea of the existence of relevant non-Gaussian effects as in the case of pure hydrogen and H_{2}-D_{2} mixtures.
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Affiliation(s)
- Daniele Colognesi
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "N. Carrara", via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Ubaldo Bafile
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "N. Carrara", via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Milva Celli
- Consiglio Nazionale delle Ricerche, Istituto di Fisica Applicata "N. Carrara", via Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy
| | - Martin Neumann
- Fakultät für Physik der Universität Wien, Strudlhofgasse 4, A-1090 Wien, Austria
| | - Eleonora Guarini
- Dipartimento di Fisica e Astronomia, Università di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | - Manh Duc Le
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Harwell Oxford, Didcot OX11 0QX, United Kingdom
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Takemoto A, Kinugawa K. Quantumness and state boundaries hidden in supercritical helium-4: A path integral centroid molecular dynamics study. J Chem Phys 2018; 149:204504. [DOI: 10.1063/1.5053988] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ayumi Takemoto
- Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women’s University, Nara 630-8506, Japan
| | - Kenichi Kinugawa
- Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women’s University, Nara 630-8506, Japan
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11
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Abe K, Yamaoka S, Hyeon-Deuk K. Isotopic Effects on Intermolecular and Intramolecular Structure and Dynamics in Hydrogen, Deuterium, and Tritium Liquids: Normal Liquid and Weakly and Strongly Cooled Liquids. J Phys Chem B 2018; 122:8233-8242. [PMID: 30095260 DOI: 10.1021/acs.jpcb.8b02596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Differences in properties such as phase-transition temperature and transport coefficients among liquids of different isotopic compositions, hydrogen, deuterium, and tritium, should originate from their differently pronounced nuclear quantum effects (NQEs) rather than from any subtle difference in the electronic interaction potentials. Accurate and efficient determination of structural and dynamical isotopic effects in the quantum liquids still remains as one of the challenging problems in condensed-phase physics. With a recently developed nonempirical real-time molecular dynamics method which describes nonspherical molecules with the NQEs, we computationally realized and investigated dynamical and quantum isotopic effects of not only traditionally studied isotopes, hydrogen, and deuterium but also a lesser known radioisotope, tritium, in broad thermodynamic conditions from normal liquid to weakly and strongly cooled liquids, which have been hindered by rapid crystallization in spite of numerous experimental attempts at supercooling. Reproducing the previously reported experimental isotope dependence on the bond length and vibrational frequencies of hydrogen, deuterium, and tritium liquids, we further demonstrate that distinctive isotope effects appear in their intermolecular and intramolecular structure and dynamics not only at lower temperature but also at higher temperature, which none has so far been able to obtain quantitative results for realistic systems. Rationalization of their physical origins and the obtained physical insights will help future experimental searching and monitoring intermolecular and intramolecular dynamics and structures of these isotopes not only in normal liquid but also in supercooled liquid.
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Affiliation(s)
- Kiharu Abe
- Department of Chemistry , Kyoto University , Kyoto 606-8502 , Japan
| | - Shutaro Yamaoka
- Department of Chemistry , Kyoto University , Kyoto 606-8502 , Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry , Kyoto University , Kyoto 606-8502 , Japan.,Japan Science and Technology Agency, PRESTO , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan
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12
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Ando K. Potential energy surfaces for electron dynamics modeled by floating and breathing Gaussian wave packets with valence-bond spin-coupling: An analysis of high-harmonic generation spectrum. J Chem Phys 2018. [DOI: 10.1063/1.5012575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Koji Ando
- Department of Information and Sciences, Tokyo Woman’s Christian University, 2-6-1 Zenpukuji, Suginami-ku, Tokyo 167-8585, Japan
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13
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Ando K. Localized electron wave packet description of chemical bond and excitation: Floating and breathing Gaussian with valence-bond coupling. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2017.02.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Abe K, Hyeon-Deuk K. Dynamical Ordering of Hydrogen Molecules Induced by Heat Flux. J Phys Chem Lett 2017; 8:3595-3600. [PMID: 28722419 DOI: 10.1021/acs.jpclett.7b01350] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Achieving a direct nonequilibrium simulation for hydrogen systems has been quite challenging because nuclear quantum effects (NQEs) have to be taken into account. We directly simulated nonequilibrium hydrogen molecules under a temperature gradient with the recently developed nonempirical molecular dynamics method, which describes nonspherical hydrogen molecules with the NQEs. We found dynamical ordering purely induced by heat flux, which should be distinguished from static ordering like orientational alignment, as decelerated translational motions and enhanced intensity of H-H vibrational power spectra despite the little structural ordering. This dynamical ordering, which was enhanced with stronger heat flux while independent of system size, can be regarded as self-solidification of hydrogen molecules for their efficient heat conduction.
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Affiliation(s)
- Kiharu Abe
- Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan
- Japan Science and Technology Agency, PRESTO , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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15
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Transport coefficients of normal liquid helium-4 calculated by path integral centroid molecular dynamics simulation. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.01.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Minamino Y, Kinugawa K. Path integral centroid molecular dynamics simulation of para-hydrogen sandwiched by graphene sheets. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.10.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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17
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HYEON-DEUK K. Quantum Molecular Dynamics Simulation of Condensed Hydrogens by Nuclear and Electron Wave Packet Approach. JOURNAL OF COMPUTER CHEMISTRY-JAPAN 2016. [DOI: 10.2477/jccj.2016-0020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Kim HYEON-DEUK
- Department of Chemistry, Kyoto University, Kyoto, 606-8502, Japan
- Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
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