Application of the molecular dynamics method and the excited state model to the investigation of the glass transition in argon

Abstract

The glass transition in argon at a high cooling rate is simulated. At a temperature of 50 K (considerably below the melting temperature T f = 83.8 K), the fluctuation volume fraction reaches the constant value f g ≅ 0.03-0.05, which is close in the order of magnitude to the criterion for the glass transition in liquids f g ≈ const 0.02-0.03 within the excited state model. At this temperature, the second maximum of the radial distribution function is split as a result of the glass transition at the temperature T g ≈ 50 K. The approximate empirical "two-thirds" rule T g ≈ (2/3) T f is reasonably satisfied for argon. The data obtained are interpreted in the framework of the excited state model.

Modification of the Ornstein-Zernike equation as applied to the vitreous state

“…The radial distribution function g 2 (r 12 ) calculated in this approximation agrees well with the data inherent in the vitreous state (Fig. 6) [3,4]. The specific feature of this approximation is that the function J(r 13 ) appears to be negative in a narrow range of distances, even though this function as a distribution function should be strictly positive.…”