The low-lying states of hydrogen fluoride: Potential energy curves for the x 1Σ+, 3Σ+, 3Π, and 1Π states

Generalized valence bond (GVB) and derived configuration interaction (CI) calculations have been carried out on the states of hydrogen fluoride (HF) which arise from ground state atoms: X 1Σ+, 3Σ+, 3Π, and 1Π. The GVB plus all single and double excitation calculations yield (with experimental constants in parentheses): De=5.72 eV (6.12 eV), Re=0.920 Å (0.9168 Å), and ωe=4158 cm−1 (4138.73 cm−1). The polarization CI (POL−CI) wavefunction is found to reproduce well the results of the more extensive calculation. The POL−CI wavefunction takes into account the internal and semi-internal correlation effects of open-shell many electron theory. A simple formula, involving Morse functions, is proposed to account for the remaining error in the ground state potential curve.