Prediction of ~1P Rydberg energy levels of beryllium based on calculations with explicitly correlated Gaussians

摘要

Benchmark variational calculations are performed for the seven lowest 1s~22s np (~1P), n = 2. . . 8, states of the beryllium atom. The calculations explicitly include the effect of finite mass of ~9Be nucleus and account perturbatively for the mass-velocity, Darwin, and spin-spin relativistic corrections. The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. Basis sets of up to 12 500 optimized Gaussians are used. The maximum discrepancy between the calculated nonrelativistic and experimental energies of 1s~22s np(~1P)→1s~22s~2 (~1S) transition is about 12 cm~(?1). The inclusion of the relativistic corrections reduces the discrepancy to bellow 0.8 cm~(?1).