Calculation of second virial coefficients using ab initio intermolecular pair potentials for F2-F2 and H2-F2 dimers

Abstract

The ab initio intermolecular pair potentials of dimers F2-F2 and H2-F2 were calculated from all constructed orientations, using the level of theory CCSD(T) and basis sets aug-cc-pVmZ (m=2, 3, 23). The complete basis set limit aug-cc-pV23Z was extrapolated by ab initio interaction energies at the level of theory CCSD(T) with two basis sets aug-cc-pVmZ (m=2, 3). Then the quantum mechanical results were used for constructing two new 5-site potential functions by fitting ab initio energies of dimers F2-F2 and H2-F2. The correlation between ab initio and the fitted ab initio energies of 5-site pair potentials for dimers F2-F2 and H2-F2 is appeared by fitness values R2 in range 0.99749–0.99997. The fitted potentials were used in standard thermodynamic relations to obtain the second virial coefficients and the results were compared to experimental data.