Theoretical Study of the CsNa Molecule: Adiabatic and Diabatic Potential Energy and Dipole Moment

Abstract

The adiabatic and diabatic potential energy curves of the low-lying electronic states of the NaCs molecule dissociating into Na (3s, 3p) + Cs (6s, 6p, 5d, 7s, 7p, 6d, 8s, 4f) have been investigated. The molecular calculations are performed using an ab initio approach based on nonempirical pseudopotential, parametrized l-dependent polarization potentials and full configuration interaction calculations through the CIPCI quantum chemistry package. The derived spectroscopic constants (Re, De, Te, ωe, ωexe, and Be) of the ground state and lower excited states are compared with the available theoretical and experimental works. Moreover, accurate permanent and transition dipole moment have been determined as a function of the internuclear distance. The adiabatic permanent dipole moment for the first nine (1)Σ(+) electronic states have shown both ionic characters associated with electron transfer related to Cs(+)Na(-) and Cs(-)Na(+) arrangements. By a simple rotation, the diabatic permanent dipole moment is determined and has revealed a linear behavior, particularly at intermediate and large distances. Many peaks around the avoided crossing locations have been observed for the transition dipole moment between neighbor electronic states.

Ab initio electronic structure and prospects for the formation of ultracold calcium–alkali-metal-atom molecular ions

“…The core polarizabilities of the Ca + ion and alkali atoms are taken to be α Ca 2+ = 3.1717 a 3 0 , α Li + = 0.1917 a 3 0 , α Na + = 0.9930 a 3 0 , α K + = 5.457 a 3 0 , α Rb + = 9.245 a 3 0 and α Cs + = 15.117a 3 0 [62-69, 71, 77]. Employed models reproduce atomic properties with good accuracy when compared with previous theoretical results and experimental measurements [62][63][64][65][66][67][68][69].…”

“…In this work, we calculate non-relativistic potential energy curves within the Born-Oppenheimer approximation for the ground and excited electronic states of calciumalkali-metal-atom molecular ions: CaAlk + (Alk=Li, Na, K, Rb, Cs). To this end, we employ the ab initio approach, which was developed and presented previously in several works on alkali hydrides [62][63][64][65], alkali-metal dimers [66][67][68][69], alkaline-earth-metal hydrides [70][71][72], and alkali-metal-alkaline-earth-metal molecular ions [73,74]. The investigated CaAlk + molecular ions, thus, are treated effectively as two-electron systems with efficient non-empirical pseudopotentials in their semi-local form [75] used to replace core electrons.…”

“…For Ca the (8s, 7p, 7d)/[8s, 7p, 5d] basis set developed in Ref. [71] [62][63][64][65][66][67][68][69]. The core polarizabilities of the Ca + ion and alkali atoms are taken to be α Ca 2+ = 3.1717 a 3 0 , α Li + = 0.1917 a 3 0 , α Na + = 0.9930 a 3 0 , α K + = 5.457 a 3 0 , α Rb + = 9.245 a 3 0 and α Cs + = 15.117a 3 0 [62-69, 71, 77].…”