Electronic states, ionization potentials, and bond energies of TlHn, InHn, TlH+n, and InH+n (n=1–3)

Abstract

Potential energy surfaces of 6 electronic states of TlH2 and InH2 and 8 electronic states of TlH+2 and InH+2 are computed. In addition the ground states of TlH3, InH3, TlH+3, InH+3, TlH, and TlH+ are investigated. A complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by second-order configuration interaction (SOCI) and relativistic configuration interaction (RCI) including spin–orbit coupling calculations are carried out. The step-wise bond energies, De(Hn−1M–H) and adiabatic ionization potentials are computed. The ground states of TlH2 and InH2 are found to be bent (2A1; θe∼121.5 °, 120 °) while the ground states of TlH+2 and InH+2 are linear (1Σ+g). The ground states of TlH3 and InH3 are found to be 1A1 (D3h ) states while the ground states of TlH+3 and InH+3 are Jahn–Teller distorted 2B2(C2v ) states. The unique bond length of TlH+3 and InH+3 is shorter than the two equal bond lengths. The bond angles (H–M–H) for TlH+3 and InH+3 deviate considerably from the neutral θe=120 ° to near 69 °. The TlH+ ion is found to be only 0.04 eV stable. Periodic trends in the geometries, bond energies and IPs are studied. Spin–orbit effects were found to be significant for TlHn species. The IPs of InHn and TlHn exhibit odd–even alternation. The bond energies also show an interesting trend as a function of n.