Superposition of Configuration Results for SI II

The method of superposition of configuration (SOC) was applied to a series of states in Si ii. The two 3s3p2 2D and 3s23d 2D configurations interacted strongly and resulted in two states that were far from orthogonal. The SOC theory was extended to include an orthogonality constraint and the upper 2D state determined orthogonal to the lower 2D state. The gf-values for a series of transitions are reported and compared with other approximations and, in a few cases, with experiment. The SOC method gives ~2 values which may differ considerably from the corresponding Hartree-Fock values. In most cases the agreement with experiment is thereby improved, but for 3d 2D -` 4f 2F it is worse. I. INTRODUCTIO