1D states of the beryllium atom: Quantum mechanical nonrelativistic calculations employing explicitly correlated Gaussian functions

摘要

Very accurate finite-nuclear-mass variational nonrelativistic calculations are performed for the lowest five1D states (1s2 2p2, 1s2 2s1 3d1, 1s2 2s1 4d1, 1s2 2s1 5d1, and 1s2 2s1 6d1) of the beryllium atom (9Be). Thewave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. Theexponential parameters of the Gaussians are optimized using the variational method with the aid of the analyticalenergy gradient determined with respect to those parameters. The calculations exemplify the level of accuracythat is now possible with Gaussians in describing bound states of a four-electron system where some of theelectrons are excited into higher angular states