М. А. Kobelev, D. О. Zakiryanov, N. К. Tkachev.
ABSTRACT
Calculations of partial structural factors of a molten lithium fluoride at a temperature of 1200 K are carried out by three methods: ab initio and classical molecular dynamics, as well as within the model of charged hard spheres in the mean-spherical approximation. It is shown that despite the general topology of the calculated partial structure factors for all three methods, the key feature of the computer simulation results is the absence of a shoulder on the right side of the first peak of the cation-cation structure factor. It is suggested that the observed difference can be related to the Buckingham softness of the repulsive part of the pair potential in the case of the classical model in molecular dynamics calculations. Calculations using by ab initio molecular dynamics also confirm this conclusion. The results of calculating the density-density structural factor by computer simulation methods demonstrate the presence of two maxima lying at k ≈ 2.4 Å-1 and k ≈ 4.4 Å-1, respectively. At the same time, within the model of charged hard spheres, there is one maximum at k ≈ 3.5 Å-1 and a small shoulder on the left, the position of which coincides with the first maximum obtained by computer simulation methods. The observed differences can be related to the fact that the calculated curve of the partial cation-anion structure factor within the framework of the model of charged hard spheres has a higher amplitude in the vicinity of the wave vector ≈ 3.5 Å-1.
KEYWORDS
structural factors, molten LiF, molecular dynamics, density functional theory
DOI: 10.31857/S0235010622060068