Electronic Structures of ScLi, TiLi, VLi, CrLi, and CuLi and Their Positive Ions

Abstract

We have studied the ground and low-lying excited states of the transition-metal lithides ScLi, TiLi, VLi, CrLi, and CuLi and their monopositive ions and report bond energies, bond lengths, and vibrational frequencies, calculated using MRCI and ACPF techniques. The ground states of ScLi (3Δ) and TiLi (4Φ) trace their lineage to the ground s2dn configuration of the transition element and are weakly bound. The ground states of CrLi (6∑+) and CuLi (1∑+) trace their lineage to the ground sdn+1 configurations and are more strongly bound. VLi (5Δ) traces its lineage to the excited sd4 configuration and is strongly bound, relative to this asymptote. The positive ions ScLi+ (2Δ), TiLi+ (3Φ), VLi+ (4Δ), and CrLi+ (7∑+) are more strongly bound than their neutral precursors, while CuLi+ (2∑+) is more weakly bound than its neutral precursor. In general, the structures of those transition-metal lithides that dissociate to the s2dn asymptote are very sensitive to electron correlation, while those that dissociate to an sdn+1 asymptote are less sensitive. The bonding in the positive ions is primarily ionic.