Velocity autocorrelation function and self-diffusion coefficient in large molecular dynamics models of liquid argon and water

Autor:	Vladimir P. Voloshin, A. V. Anikeenko, Yuri I. Naberukhin
Rok vydání:	2021
Předmět:	Molecular dynamics Self-diffusion Materials science Computer Networks and Communications Hardware and Architecture Materials Science (miscellaneous) Autocorrelation Liquid argon Physics::Chemical Physics Molecular physics Information Systems Electronic Optical and Magnetic Materials
Zdroj:	Radioelectronics. Nanosystems. Information Technologies.. 13:149-156
ISSN:	2414-1267 2218-3000
Popis:	Autocorrelation function of the particle velocity Z(t) is calculated using the molecular dynamics method in the models of liquid argon and water. The large size of the models (more than a hundred thousand particles) allowed us to trace these functions up to 50 picoseconds in argon and up to 10 picoseconds in water, and to achieve a calculation accuracy sufficient for analytical analysis of their shape. The difference in the determination of the self-diffusion coefficient using Einstein's law and the integral of Z(t) (Green-Kubo integral) is analyzed and it is shown to be 3% at best when t is of the order of several picoseconds. The asymptote of the function Z(t) in argon is close to the power law αt–3/2 predicted by hydrodynamics, but with an amplitude that depends on the time interval under consideration. In water, the asymptote of Z(t) has nothing in common with that in argon: it has α < 0 and the exponent is close to -5/2, and not to -3/2.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::aa2688af9536e2746f27e8c755ff0a0d https://doi.org/10.17725/rensit.2021.13.149 Zobrazit plný text záznamu