Abstract
Full configuration interaction (FCI) calculations have been performed for the /sup 3/F and /sup 5/F states of Ti atom and the /sup 4/Phi and /sup 2/..delta.. states of TiH. The FCI calculations are compared to approximate treatments of the correlation problem; for the /sup 2/..delta.. state, the CASSCF/MRCI treatment agrees with the FCI results for r/sub e/, omega/sub e/, the dipole moment, and the dipole derivative. For the /sup 4/Phi state, the CASSCF/MRCI approach agrees well with the FCI for r/sub e/, omega/sub e/, and D/sub e/. However, the agreement between CASSCF/MRCI and FCI treatments for the dipole moment is not as good, even when the CASSCF and MRCI reference spaces contain up to 800 CSFs. Natural orbital iterations improve the dipole moment but have a smaller effect on the other spectroscopic parameters. The CPF and MCPF methods agree well with the FCI for the /sup 4/Phi state, which is reasonably well described by the SCF; this is true even for the dipole moment, where a natural orbital iteration must be performed for the CASSCF/MRCI treatment. The CPF and MCPF treatments do not agree as well for the /sup 2/..delta.. state, which is not as well described by the SCF.
Published Version
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