A summary is given of our recently developed semiempirical pseudopotentials and their applications, and new results are presented on the K, molecule.A core-polarization potential [ 1-31 is incorporated into semiempirical pseudopotentials [46]. The pseudopotential for the atom with core A is QA, Q" are core charges, P: is the projector on angular symmetry 1 with respect to core A, B: and P: are adjusted to the valence and Rydberg spectra of one-valence-electron atoms or ions, a h is the dipole polarizability of core A, FA the electric field at core A due to the valence electrons and the other cores, and p is a polarization cut-off parameter.For molecules, the pseudopotentials become geometry dependent. It is found that (a) core polarization accounts for core-valence correlation almost quantatively [l-81; (b) it corrects errors of the frozen-core approximation in pseudopotentials [4-61; and ( c ) the relativistic contraction of the valence orbitals is reproduced [5-71, e.g., yielding very good atomic polarizabilities for Rb, Cs, Cu, Ag, and Au [7,9].For alkali dimer ions, very accurate potential curves are obtained and a number of predictions is given [4-61. The adiabatic ionization energies of the homo-and heteronuclear alkali dimers are evaluated by a thermocycle [5]. The potential curves for the excited A 'X+ state of the nonpolar alkali dimers are found almost parallel to those for the ground state of the corresponding dimer cations [lo]. This rule allows predictions [5, 101 of spectroscopic constants not yet measured or calculated.
