title: High-frequency asymptote for the velocity auto-correlation function spectrum of argon-like systems.
abstract: The work is devoted to the analysis of high-frequency behavior of the velocity auto-correlation function spectrum ϕ(V)(ω) for argon-like systems. The theoretical predictions are compared with results of computer simulations of ϕ(V)(ω). It is shown that (1) ϕ(V)(ω) takes the exponential behavior ϕ(V)(ω)⇒ω(q(n)) (ω→∞)exp(-(ωτ(a)(n))(p(n))), where p(n), q(n), and τ(a)(n) are the definite functions of the steepness exponent n for the power repulsive part of interparticle potential; (2) there is full agreement between theoretical predictions and the values of p(n), q(n), and τ(a)(n) obtained in computer simulations. Weighty arguments about the universal character of the exponential frequency decay exp(-(ωτ(a)(n))(p(n))) for spectra of different correlation functions are given. The experimental spectrum of the depolarized light scattering in argon for high frequencies is analyzed. It is shown that the steepness exponent n for the power repulsive potential takes the value: n ≈ 24 that is essentially different from n = 12 characteristic for the Lennard-Jones potential.
authors: Department of Molecular Physics, Kiev Taras Shevchenko National University, Kiev 03680, Ukraine.
authors: V Yu
authors: VY
authors: Bardik
authors: N P
authors: NP
authors: Malomuzh
authors: K S
authors: KS
authors: Shakun