Optimized parameters and exponents of Mie (n,m) intermolecular potential energy function based on the shape of molecules

Abstract

Through the use of the second virial coefficient data, optimized parameters and exponents of the Mie (n,m) potential energy function are derived for a number of symmetric groups of molecules. In the optimizations performed, parameters of the potential function are varied for each molecule, but the exponents of the potential function are taken as functions of the shape of the groups of molecules considered. It is concluded that the attractive exponent, m = 7, is shared by all the symmetric groups considered. The repulsive exponent, n, is varied according to the shape of the molecules. Also, in this report, newly calculated parameters of the Lennard-Jones (12,6) and Mie (14,7) potential energy functions for 33 different symmetric and nonsymmetric molecules are reported. Results indicate that, generally, the Mie (14,7) pair-potential energy function is a better fit for the second virial coefficient data than the Lennard-Jones (12,6) function.