Calculation of Spectroscopic Characteristics of Alkali-Metal Dimers on the Basis of a Model Perturbation Theory

摘要

The problem of calculation of some alkali-metal diatomic molecules NaM in homonuclear and heteronuclear variants (M = Li, Na, K, Rb, Cs, and Fr) is considered on the basis of the pseudopotential approach within the framework of a formally exact perturbation theory of the Rayleigh-Schrodinger type with an initial potential of the zero-order approximation. Calculated values of energy parameters, in particular, the dissociation energies are presented, some of which are obtained for the first time. Results of calculations of the energies of Rydberg states n~1Σ_g~+ (n = 4, 5) and the spectroscopic constants of the sodium dimer are presented. The calculation shows that two main effects of the second-order perturbation theory-the polarization interaction of valence particles via the core and their mutual screening by each other-are of importance in achieving an acceptable accuracy. The contribution of core excitations is fundamental for Rydberg states.