Structures and analytical potential energy functions of the ground states of YⁿO (n=16, 17, 18) molecules

Based on effective core potential of Y atom. selecting 6-311 + G (3df), AUG-cc-PVTZ basis sets for O atom. the energies, equilibrium structure and harmonic frequency of the ground states of YⁿO (n=16) molecules are calculated using density functional theory (B3LYP). Based on the theory of atomic and molecular statics, the reasonable dissociation limit of the ground states of YⁿO (n=16, 17, 18) molecules are derived. By comparing the results of calculations with the existing experimental values, we consider that the mixed basis sets CRENBL ECP/AUG-cc-PVTZ is the most suitable for the calculation of the molecules. Consequently, optimization and frequency calculation have been done for YⁿO (n= 17,18) and the potential energy surface of the ground states of YO molecule has been Scanned at the B3LYP/ CRENBL ECP/AUG-cc-PVTZ level of the theory. The potential energy curves of the ground states are obtained by least square fitting to the Murrell-Sorbie potential energy function. The spectroscopic constants (B_e, α_e, ω_e, ω_eχ_e, D_e) and force constants (f₂, f₃, f₄) are calculated and compared with experimental results. It indicate that the results of calculations are in good agreement with the experimental data. (authors)