ELECTRONIC STATES AND NATURE OF BONDING IN THE MOLECULE YN BY ALL-ELECTRON ABINITIO CASSCF CALCULATIONS

In the present work, we present results of all-electron ab initio CASSCF calculations of nine electronic states of the molecule YN. Also reported are the spectroscopic constants derived on the basis of the calculated potential energies. The predicted electronic ground state,is 1SIGMA+, and this state is found to be separated from the excited states 3SIGMA+, 3PI, and 1PI by 5177, 9290, and 9915 cm-1, respectively. The chemical bond in the YN molecule is polar with charge transfer from Y to N, giving rise to a dipole moment of 8.19 Debye at 3.3 au in the 1SIGMA+ ground state. The chemical bond in the 1SIGMA+ ground state is basically a double bond composed of two pi bonds. The dissociation energy of the YN molecule has been derived as 4.59 eV.