All Electron ab initio Investigations of the Electronic States of the MoN Molecule

The low lying electronic states of the molecule MoN have been investigated by performing all electron ab initio multi-configuration self-consistent-field (CASSCF) calculations. The relativistic corrections for the one electron Darwin contact term and the relativistic mass-velocity correction have been determined in perturbation calculations.

The electronic ground state is confirmed as being 4 . The chemical bond of MoN has triple bond character due to the approximately fully occupied delocalized bonding and orbitals. The spectroscopic constants for the ground state and ten excited states have been derived. The excited doublet states, 2 , 2 , 2 , and 2 + are found to be lower lying than the 4 state that has been investigated experimentally.

Elaborate multi configuration configuration interaction (MRCI) calculations have been carried out for the states 4 and 4 using various basis sets. The spectroscopic constants for the 4 ground state have been determined as re = 1.636 Å and e = 1109 cm-1, and for the 4 state as re = 1.662 Å and e = 941 cm-1.

The values for the ground state are in excellent agreement with available experimental data. The MoN molecule is polar with charge transfer from Mo to N. The dipole moment has been determined as 2.11 D in the 4 state and as 4.60 D in the 4 state. The latter value is in excellent agreement with the experimental value determined from molecular Stark spectroscopic measurements.

The dipole moment for the 4 state determined in the present work is 1.27 D less than the experimental value. This suggests an reinvestigation of the experiment. The dissociation energy, De, is determined as 5.17 eV, and D0 as 5.10 eV.