Electronic Excited States Calculated Using Generalized Spin-Orbital Functions Including Spin-Orbit Interactions

Abstract

We examined an equation-of-motion coupled-cluster (EOM-CC) method, which is basically equivalent to the SAC-CI method, starting from the generalized unrestricted Hartree-Fock (GUHF) wave function incorporated with a spin-dependent relativistic Hamiltonian. Demonstrations of the present method were carried out for the spin-orbit (SO) splitting energies of ³P and ²P states of relatively light atoms (Be - Ar). Although we considered only the lowest-order (c^-2) Breit-Pauli one- and two-electron SO terms, it was found that the SO splitting energies calculated by the present method agree well with experimental ones, and are almost equivalent to those obtained by some conventional higher-order relativistic and electron-correlated methods.