THE LOW-LYING STATES OF THE 2ND-ROW TRANSITION-METAL HYDRIDES (YH-CDH)

Complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by full second-order configuration interaction calculations which included up to 713 000 configurations are carried out on the low-lying states of all second-row transition metal hydrides (YH-CdH). A large (6s5p5d 1f) valence Gaussian basis set together with relativistic effective core potentials which included the outer 4s24p64d n5s2 shells, were employed. The spectroscopic constants and potential energy curves of six electronic states of CdH are also obtained and compared with available experimental spectra. The ground states of YH, ZrH, NbH, MoH, TcH, RuH, RhH, PdH, AgH, and CdH were found to be 1Σ+, 2Σ3/2, 3(I), 6Σ+, 5Σ+, 4Σ1/2-, 3Δ, 2Σ+, 1Σ +, and 2Σ+, respectively. For NbH, TcH, and RuH, 5Π, 7Σ+, and 4Φ states, respectively, were found to be close to the ground states. The 5Π3 and 5Δ3 states of NbH undergo avoided crossing. The spectroscopic constants (r e, μe, De, ωe, T e) of the low-lying states of these hydrides are computed and compared with available data on YH, RhH, PdH, and AgH. The theoretical r e and ωe values are within 0.01 Å and 20 cm-1 of the experimental constants for these three hydrides. © 1990 American Institute of Physics.