A molecular dynamics study of nuclear quantum effect on diffusivity of hydrogen molecule

H Nagashima; S Tsuda; N Tsuboi; A K Hayashi; T Tokumasu

doi:10.1063/1.4991732

A molecular dynamics study of nuclear quantum effect on diffusivity of hydrogen molecule

J Chem Phys. 2017 Jul 14;147(2):024501. doi: 10.1063/1.4991732.

Authors

H Nagashima¹, S Tsuda², N Tsuboi³, A K Hayashi⁴, T Tokumasu⁵

Affiliations

¹ Department of Mechanical Systems Engineering, University of the Ryukuys, Okinawa, Senbaru, Nishihara-cho, Okinawa 903-0213, Japan.
² Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan.
³ Department of Mechanical and Control Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan.
⁴ Department of Mechanical Engineering, Aoyama Gakuin University, Sagamihara 229-8558, Japan.
⁵ Institute of Fluid Science, Tohoku University, Sendai 980-8577, Japan.

PMID: 28711051
DOI: 10.1063/1.4991732

Abstract

In this paper, the nuclear quantum effect of the hydrogen molecule on its diffusivity was analyzed using the molecular dynamics (MD) method. The centroid MD (CMD) method was applied to reproduce the time evolution of the molecules. The diffusion coefficient of hydrogen was calculated using the Green-Kubo method over a wide temperature region, and the temperature dependence of the quantum effect of the hydrogen molecule on its diffusivity was addressed. The calculated results were compared with classical MD results based on the principle of corresponding state (PCS). It was confirmed that the difference in the diffusion coefficient calculated in the CMD and classical MD methods was small, and the PCS appears to be satisfied on the temperature dependence of the diffusion coefficient, even though the quantum effect of the hydrogen molecules was taken into account. It was clarified that this result did not suggest that the quantum effect on the diffusivity of the hydrogen molecule was small but that the two changes in the intermolecular interaction of hydrogen due to the quantum effect offset each other. Moreover, it was found that this tendency was related to the temperature dependence of the ratio of the kinetic energy of the quantum fluctuational motion to the classical kinetic energy.