New inversion and ab initio intermolecular potentials for supercritical fluorine: Calculation of some properties and MD simulation

Abstract

A new pair-potential energy function of fluorine has been determined via the inversion of reduced viscosity collision integrals. The potential reproduces the second virial coefficient, viscosity, and thermal conductivity of supercritical fluorine in good accordance with experimental data. We have also determined the (F2)2 potential using different ab initio methods at different geometries. Molecular dynamics simulation has been also performed to obtain pressure of supercritical fluorine using the inversion pair-potential supplemented by Feynman–Hibbs quantum correction and the weighted ab initio potential using the CCSD(T)/aug-pvdz method. To consider many-body interactions, the simple three-body potential of Hauschild and Prausnitz [7] used with the inversion potential to improve the properties without requiring an expensive three-body calculation. We have also calculated the three-body interactions for (F2)3 system using the ab initio computations at different orientations. Our results indicated that the three-body potentials improve the two-body supercritical values.