Theoretical study of the dipole moment function of the A 1Σ+ state of LiH

Abstract

A theoretical study of the A 1Σ+ 7LiH dipole moment function is reported. A new theoretical A 1Σ+ potential energy curve, obtained by accounting for essentially all of the electron correlation within a large flexible Slater basis set, is reported here for the first time. The calculated equilibrium geometry (Re) and dissociation energy (De) of this new potential are in close agreement with experimental values (given in parentheses): 4.825 (4.883) bohr and 8653 (8682) cm−1, respectively. The vibrational spacings (ΔGv+(1/2)) for all levels (0⩽v⩽26) are also in agreement with experiment. The dipole moment function derived from this potential, as well as the previous theoretical dipole moment functions of Partridge and Langhoff and of Docken and Hinze, are used to obtain vibrationally averaged dipole moments μv for all of the vibrational levels of the A 1Σ+ state of 7LiH. Of particular interest is μ5, the dipole moment for the v = 5 level, measured recently by two separate experimental methods. Experimentally, the sign of μ5 is uncertain, but these theoretical results strongly suggest that μ5 is negative (i.e., Li−H+).