Excitation energies and oscillator strengths of CaI using multireference many-body perturbation theory

Excitation energies and oscillator strengths of neutral calcium (Ca I) are calculated through third order using a variant of the multireference many-b ody perturbation theory, known as the effective valence-shell Hamiltonian ( H-v) method. Transition energies, oscillator strengths, and binding energie s of various states are computed and compared with experimental and other t heoretical data. These quantities are in favorable agreement with the exper iment and other correlated calculations. The basis and valence space depend ence of the H-v scheme are addressed with some illustrative examples. [S105 0-2947(99)06905-X].