Ab Initio Potential Curves And Spectral Properties Of Lu₂ And B₂～(++)

The multi-reference configuration interaction(MRCI) method and effective-core-potential(ECP) basis set have been used to calculate the equilibrium geometries, dislocation energies and potential energy curves(PECs) of nine states of Lu₂ dimer. The analytical potential energy functions (APEFs) of these states have been fitted using Murrell-Sorbie(MS) function and least square fitting method. Based on this, the spectroscopic parameters of each state are calculated and compared with the theoretical and the experimental values available at present. The vibrational levels for each state of Lu₂ are determined by solving Schr?dinger equation of nuclear motion.The MRCI method and aug-cc-pvqz (AVQZ) have been used to calculate PECs of the singlet and triplet states of the∏_u and∏_g symmetry of B₂⁺⁺. All of the 4 states (¹âˆ_u, ¹âˆ_g, ³âˆ_u and ³âˆ_g) are found to be metastable states. Based on the PECs, the APEFs of these states have been fitted using the least square fitting method and two models of functions. The spectroscopic parameters of each state are also calculated, and compared with other investigations in the literature. The credibility and veracity of the two functions are evaluated. Some ideas to improve the fitting accuracy are presented. Also the vibrational levels for each state are predicted by solving Schr?dinger equation of nuclear motion.As the experimental works for these systems are not abundant, some results such as the spectroscopic constants and vibrational levels have no experimental values to compare with. Therefore, our present researches can provide us with beneficial reference for further experimental and theoretical studies of the dimers. The present APEFs can be used to construct many-body potential energy functions which have further applications in molecular reaction dynamics.