Theoretical electronic structure with rovibrational studies of the molecules YP, YP and YP.

Due to the absence of the electronic structure of the YP molecule and its ions in literature, this work is conducted via an ab initio Complete Active Space Self Consistent Field and the Multi-Reference Configuration Interaction with Davidson correction calculation (CASSCF/MRCI + Q) to investigate the low-lying electronic states of these molecules. Adiabatic potential energy curves (PECs) along with static dipole moment (DM) curves for 27, 24, and 21 low-lying electronic states in the representation of Λ for YP, YP, and YP molecules have been investigated, respectively. For the low-lying electronic states of the YP molecule and their anion and cation, the spectroscopic constants Re, T, ωe, ωex, Be, D are provided. The rovibrational constants E, B, D, and the abscissa of turning points R and R (up to vibrational level v = 37) are calculated using the canonical functions approach and referring to the calculated data from the PECs. Perturbation theory method is also used to compare our data's validity, as no results are presented in the literature for these molecules.