I. Shim et Ka. Gingerich, ELECTRONIC STATES AND NATURE OF BONDING IN THE MOLECULE MOC BY ALL-ELECTRON AB-INITIO CALCULATIONS, The Journal of chemical physics, 106(19), 1997, pp. 8093-8100
In the present work all electron ab initio multiconfiguration self-con
sistent-held (CASSCF) and multireference configuration interaction (MR
CI) calculations have been carried out to determine the low-lying elec
tronic states of the molecule MoC. The relativistic corrections for th
e one electron Darwin contact term and the relativistic mass-velocity
correction have been determined in perturbation calculations. The elec
tronic ground state is predicted as (3) Sigma(-). The spectroscopic co
nstants for the (3) Sigma(-) electronic ground state and eight low-lyi
ng excited states have been derived by solving the Schrodinger equatio
n for the nuclear motion numerically. Based on the results of the CASS
CF calculations the (3) Sigma(-) ground state of MoC is separated from
the excited states (3) Delta, (5) Sigma-, (1) Sigma, (1) Delta, (5) P
i, (1) Sigma(+), and (3) Pi by transition energies of 4500, 6178, 7207
, 9312, 10 228, 11 639, and 16 864 cm(-1), respectively. The transitio
n energy between the (3) Sigma(-) ground state and the (3) Pi state as
derived in the MRCI calculations is 15 484 cm(-1). For the (3) Sigma(
-) ground state the equilibrium distance has been determined as 1.688
Angstrom, and the vibrational frequency as 997 cm(-1). The chemical bo
nd in the (3) Sigma(-) electronic ground state has triple bond charact
er due to the formation of delocalized bonding rr and a orbitals. The
chemical bond in the MoC molecule is polar with charge transfer from M
o to C, giving rise to a dipole moment of 6.15 D at 3.15 a.u. in the (
3) Sigma(-) ground state. (C) 1997 American Institute of Physics.