Atomic motion from the mean square displacement in a monatomic liquid
Abstract
VT theory is constructed in the manybody Hamiltonian formulation, and is being developed as a novel approach to liquid dynamics theory. In this theory the liquid atomic motion consists of two contributions, normal mode vibrations in a single representative potential energy valley, and transits, which carry the system across boundaries between valleys. The mean square displacement time correlation function (the MSD) is a direct measure of the atomic motion, and our goal is to determine if the VT formalism can produce a physically sensible account of this motion. We employ molecular dynamics (MD) data for a system representing liquid Na, and find the motion evolves in three successive time intervals: on the first 'vibrational' interval, the vibrational motion alone gives a highly accurate account of the MD data; on the second 'crossover' interval, the vibrational MSD saturates to a constant while the transit motion builds up from zero; on the third 'random walk' interval, the transit motion produces a purely diffusive random walk of the vibrational equilibrium positions. Furthermore, this motional evolution agrees with, and adds refinement to, the MSD atomic motion as described by current liquid dynamics theories.
 Authors:

 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Descartes Labs, Los Alamos, NM (United States)
 Publication Date:
 Research Org.:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1291293
 Report Number(s):
 LAUR1526631
Journal ID: ISSN 09538984
 Grant/Contract Number:
 AC5206NA25396
 Resource Type:
 Accepted Manuscript
 Journal Name:
 Journal of Physics. Condensed Matter
 Additional Journal Information:
 Journal Volume: 28; Journal Issue: 18; Journal ID: ISSN 09538984
 Publisher:
 IOP Publishing
 Country of Publication:
 United States
 Language:
 English
 Subject:
 74 ATOMIC AND MOLECULAR PHYSICS; Theory, Liquids, Selfdiffusion; Liquid theory; Hamiltonian; atomic motion in liquids; statistical mechanics
Citation Formats
Wallace, Duane C., De LorenziVenneri, Giulia, and Chisolm, Eric D. Atomic motion from the mean square displacement in a monatomic liquid. United States: N. p., 2016.
Web. doi:10.1088/09538984/28/18/185101.
Wallace, Duane C., De LorenziVenneri, Giulia, & Chisolm, Eric D. Atomic motion from the mean square displacement in a monatomic liquid. United States. doi:10.1088/09538984/28/18/185101.
Wallace, Duane C., De LorenziVenneri, Giulia, and Chisolm, Eric D. Fri .
"Atomic motion from the mean square displacement in a monatomic liquid". United States. doi:10.1088/09538984/28/18/185101. https://www.osti.gov/servlets/purl/1291293.
@article{osti_1291293,
title = {Atomic motion from the mean square displacement in a monatomic liquid},
author = {Wallace, Duane C. and De LorenziVenneri, Giulia and Chisolm, Eric D.},
abstractNote = {VT theory is constructed in the manybody Hamiltonian formulation, and is being developed as a novel approach to liquid dynamics theory. In this theory the liquid atomic motion consists of two contributions, normal mode vibrations in a single representative potential energy valley, and transits, which carry the system across boundaries between valleys. The mean square displacement time correlation function (the MSD) is a direct measure of the atomic motion, and our goal is to determine if the VT formalism can produce a physically sensible account of this motion. We employ molecular dynamics (MD) data for a system representing liquid Na, and find the motion evolves in three successive time intervals: on the first 'vibrational' interval, the vibrational motion alone gives a highly accurate account of the MD data; on the second 'crossover' interval, the vibrational MSD saturates to a constant while the transit motion builds up from zero; on the third 'random walk' interval, the transit motion produces a purely diffusive random walk of the vibrational equilibrium positions. Furthermore, this motional evolution agrees with, and adds refinement to, the MSD atomic motion as described by current liquid dynamics theories.},
doi = {10.1088/09538984/28/18/185101},
journal = {Journal of Physics. Condensed Matter},
number = 18,
volume = 28,
place = {United States},
year = {2016},
month = {4}
}
Web of Science