Ground-state properties of alkali dimers and their cations (including the elements Li, Na, and K) from <i>a</i> <i>b</i> <i>i</i> <i>n</i> <i>i</i> <i>t</i> <i>i</i> <i>o</i> calculations with effective core polarization potentials

Abstract

Extensive all-electron SCF and valence CI calculations are presented for alkali dimer systems with consideration of intershell correlation effects by use of an effective core polarization potential (CPP), which contains only a single adjustable atomic parameter. High accuracy is obtained for the ground-state spectroscopic constants of the studied molecules. The maximum deviations from accurate experimental data are as follows: 1% or 0.03 Å for Re, 2% or 100 cm−1 for De, 0.5% or 1 cm−1 for ωe, and 0.2% or 100 cm−1 for ionization energies. For experimentally uncertain or unknown values reliable predictions can thus be made. The calculated dipole moments for LiK and NaK agree with experiment to within 0.1%, but for LiNa we obtain a deviation of 8% or 0.036 D. An analysis of molecular core polarization contributions reveals the reasons for some systematic defects in previous pseudopotential calculations.