Molecular Dynamics Studies on the Soft-Core Model

概要

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Molecular dynamics studies are made on the soft-core model with a pair potential φ(r)=C/r^<12>, (C>0). Equation of states, self-diffusion constants, velocity autocorrelation functions (v. a. f.) and radial distribution functions (r .d .f.) are computed for a wide range of reduced density ρ^*=0.05〜1.9, where ρ^*=(N/V)(C/kT)^<1/4> and N/V is a number density. ρ_f^*=1.15 and ρ_m^*=1.19 correspond to the freezing and melting reduced densities, respectively. For ρ^* ≲ 0.5, the system is gas-like in a sense that the v. a. f. is not oscillatory and the r. d. f. has only a single peak. For ρ^* ≳ 0.5, the v. a. f. becomes oscillatory and the r. d. f. has more than one peak, in contrast with the hard-core system for which no oscillation of the v. a. f. is observed at all in the fluid phase. In this sense the system behaves like liquid between ρ^* ≃ 0.5 and 1.15. Around ρ^* ≃ 1.35, the self-diffusion constant drops abruptly, indicating the limit of supercooling of a kind of glass transition. Comparisions are made with the result of the hard-core system. Diffusion constants of Kr and Lennard-Jones system are found to be well fitted by the soft-core model.
理論物理学刊行会の論文
1974-10-25