Bound and quasi-bound states of the Li…FH van der Waals molecule: The effects of the potential energy surface and of the basis set superposition error

摘要

Four potential energy surfaces (PESs) for the ground electronic state of the LiFH system were constructed by fitting the energies obtained in coupled-cluster (CCSD(T)) and multi-reference configuration interaction (MRCI) calculations. Two potentials were constructed by fitting the CCSD(T) energies corrected for the effects of the basis set superposition error (BSSE) and monomer deformation. The third potential was constructed by fitting the BSSE-uncorrected CCSD(T) data. The fourth potential was constructed by fitting the energies obtained with the MRDCI variant of the MRCI method. All four PESs were used to calculate bound and quasi-bound ro-vibrational states of the Li…FH complex. The calculations of the bound-state energies, energy positions and widths of the quasi-bound states, and densities of the scattering states provided useful insights into the effects of BSSE, ab initio method employed, and fitting procedure on spectroscopic and dynamical characteristics of the Li…FH complex. It was demonstrated that the MRDCI and BSSE-corrected CCSD(T) potentials are similar from the spectroscopic and dynamical point of view, while there is a substantial difference between the MRDCI and BSSE-uncorrected CCSD(T) potentials. Information about the Li…FH ro-vibrational resonances was used to provide new insights into the dynamics of the photo-induced Li + HF → LiF + H reaction, in which products are obtained by exciting the HF fragment in the Li…FH complex with the infrared radiation.