MRD-CI potential surfaces using balanced basis sets. III. HCl and N2

Abstract

Multireference configuration interaction methods are used to calculate potential curves, dissociation energies, and vibration-rotation energy levels for HCl and N2. These calculations use basis sets optimized in a previous study. The potential curves show very good agreement with experimental (RKR) data. Both CI and RKR data are accurately fitted by five-parameter generalized Morse functions. Spectroscopic parameters calculated for HCl are De=4.62 eV, Re=1.277 Å, ωe=3023 cm−1, ωexe=52.9 cm−1, Be=10.67 cm−1, and αe=0.338 cm−1 (experimental v, J values give 4.62 eV, 1.275 Å, 2989 cm−1, 51.2 cm−1, 10.71 cm−1, and 0.341 cm−1, respectively) and for N2 are De=9.96 eV, Re=1.106 Å, ωe=2344 cm−1, ωexe=13.9 cm−1, Be=1.934 cm−1, αe=0.014 cm−1 (experimental v, J values give 9.91 eV, 1.098 Å, 2363 cm−1, 14.7 cm−1, 1.960 cm−1, and 0.015 cm−1, respectively). This good agreement with experiment is obtained using small but carefully balanced basis sets containing bond functions, an approach which we suggest should be adopted in calculations involving molecular dissociation.