Electronic states and nature of bonding in the molecule RhN by all-electron ab initio calculations

Autor: Kim Mandix, Irene Shim, Karl A. Gingerich
Rok vydání: 1997
Předmět:
Zdroj: Journal of Molecular Structure: THEOCHEM. 393:127-139
ISSN: 0166-1280
DOI: 10.1016/s0166-1280(96)04802-6
Popis: In the present work, all-electron ab initio multi-configuration self-consistent-field (CASSCF) and multi-reference configuration interaction (MRCI) calculations have been carried out to determine the low-lying electronic states of the molecule RhN. In addition, the relativistic corrections for the one-electron Darwin contact term and the relativistic mass-velocity correction have been determined in perturbation calculations. The spectroscopic constants for the seven low-lying electronic states have been derived by solving the Schrodinger equation for the nuclear motion numerically. The predicted ground state of RhN is 1 ∑ + , and this state is separated from the states 3 Π , 1 Π , 5 Δ , 3 ∑ − , 3 Δ and 1 Δ by transition energies of 1833, 4278, 6579, 8042, 9632, and 13886 cm −1 , respectively. For the 1 ∑ + ground state, the equilibrium distance has been determined as 1.640 A, and the vibrational frequency as 846 cm −1 . The chemical bond in the 1 ∑ + electronic ground state has triple bond character due to the formation of delocalized bonding π and σ orbitals. The chemical bond in the RhN molecule is polar with charge transfer from Rh to N giving rise to a dipole moment of 2.08 Debye at 3.1 a.u. in the 1 ∑ + ground state. An approximate treatment of the spin-orbit coupling effect shows that the lowest-lying spin-orbit coupled state is 0 + . This state is essentially derived from the 1 ∑ + ground state. The second and third state, 0 + and 0 − , mainly arise from the 3 Π state. The dissociation energy of the RhN molecule in its 1 ∑ + ground state has been derived as 1.74 eV.
Databáze: OpenAIRE