ИСТИНА

Often times the most efficient laser cooling pathways require the use of weakly bound states close to the dissociation limits as intermediate steps. The exact singlet/triplet composition of these states as well as their exact energies and radiative properties must therefore be known in advance with high precision and accuracy. Unfortunately, these states are heavily influenced both by the exact shape of the potential energy curve (PEC) and by the asymptotic behavior of the spin allowed transition dipole moments (TDMs) and spin-orbit coupling (SOC) matrix elements. Thus, having correct long range TDM and SOC functions, together with the relevant PECs [1,2], could be applied to the comprehensive coupled-channel (CC) treatment of the competitive radiative and predissociative dynamics of the mutually perturbed rovibronic states located in the vicinity of dissociation thresholds The asymptotic behavior of spin allowed TDMs and SOC matrix elements between electronic states converging to the lowest three dissociation limits were investigated for the lightest heteronuclear alkali diatomics XY (X,Y={Li,Na,K,Rb}). The TDM and SOC functions are evaluated in the basis of the spin-averaged wavefunctions corresponding to pure Hund’s coupling case (a) by means of effective core pseudopotentials. The electronic correlation is accounted for by applying the multi-reference configuration interaction method to only two valence electrons for all considered molecules and core-polarization potentials are used to take the core–valence effect into account. In this work, the leading asymptotic behavior of the TDM and SOC functions has been found to be R-3 and R-6. Additionally, in the case of the TDM functions, our ab initio results [3] have been found to coincide with their analytical counterparts obtained within the framework of the long-range perturbation theory by Chu and Dalgarno [4]. The study was funded by RFBR according to the bilateral Russia-Bulgaria research project 17-53-18006. References Journal (abbreviated), year, volume, first page [1] Chem. Phys.,2000, 256, 1 [2] J. Mol. Spectrosc.,2000, 203, 235. [3] PCCP, 2018, 20, 1889. [4] Phys. Rev. A, 2002, 66, 024701.