Calculation of intermolecular potentials for H₂–H₂ and H₂–O₂ dimers ab initio and prediction of second virial coefficients

Pham, Van TatDeiters, Ulrich K.2023-09-132023-09-132015http://10.1.1.182:8080/handle/123456789/13748The intermolecular interaction potentials of the dimers H₂–H₂ and H₂–O₂ were calculated from quan-tum mechanics, using coupled-cluster theory CCSD(T) and correlation-consistent basis sets aug- cc-pVmZ (m = 2, 3); the results were extrapolated to the basis set limit aug-cc-pV23Z. The interaction energies were corrected for the basis set superposition error with the counterpoise scheme. For comparison also Møller–Plesset perturbation theory (at levels 2 to 4) with the basis sets aug-cc-pVTZ were considered, but the results proved inferior. The quantum mechanical results were used to construct analytical pair potential functions. From these functions the second virial coefficients of hydrogen and the cross virial coefficients of the hydrogen–oxygen system were obtained by integration; in both cases corrections for quantum effects were included. The results agree well with experimental data, if available, or with empirical correlations.enIntermolecular potentials; dimers ab initio; second virial coefficientsCalculation of intermolecular potentials for H₂–H₂ and H₂–O₂ dimers ab initio and prediction of second virial coefficientsArticle