Electronic states of CsLi and CsLi+ molecules

Abstract

The results of the present many-electron configuration interaction calculations on the cation support the previous core-polarization effective potential calculations. The present calculations on the CsLi molecule are complementary to previous theoretical work on this system, including recently observed electronic states that had not been calculated previously. We have used an ab initio approach involving a nonempirical pseudopotential for the Li (1s 2 ) and Cs cores and a core-valence correlation correction. A very good agreement of data from spectroscopic constants for some of the lowest states of the CsLi and CsLi + molecules with those available in recent theoretical works has been obtained. The existence of numerous avoided crossings between electronic states of 2 Σ + and 2 Π symmetries is related to a charge transfer process between the two ionic CsLi + and LiCs + systems.Introduction. The research on ultracold molecules presents a current and great challenge to a spectroscopic study of alkali dimers because of both their importance in the cooling and trapping of atoms [1, 2] and molecules [3][4][5][6] and the role in high-precision spectroscopy [7][8][9]. Ultracold molecules should prove to be useful in spectroscopy and the study of molecular structure, especially in ultrahigh resolution spectroscopy which requires cold and trapped samples. Neutral-atom collisions at ultracold temperatures may be characterized by s-wave scattering lengths. Collisions of ions and atoms involve higher-order partial waves because of the long-range attractive polarization forces and differ due to the charge transfer.Another especially promising area will be the study of collisions between ultracold molecules in a regime where they will behave like waves, which perhaps may give rise to new chemistry [10][11][12]. Cooling and manipulating the cold molecules is likely to open up new branches of research. There are experiments aimed at studying polar molecular systems in order to measure the electron's permanent electric dipole moment (EDM), the lifetime of long-lived energy levels, and the effects of dipole-dipole interactions on the molecular sample properties [13]. Recent advances in precision control of an optical spectrum emitted by a femtosecond laser have made a revolutionary impact on the fields of optical frequency metrology (via self-referenced, ultra-broad bandwidth frequency combs) and ultrafast optical science (via carrier-envelope phase stabilized pulse trains). These advances have, in effect, provided an entirely new class of optical sources available for experimental investigations, which are the femtosecond lasers + cold atoms/molecules. The use of pseudopotentials for Li and Cs cores reduces the number of active electrons to only one valence electron, where a self-consistent field (SCF) calculation produces the exact energy in the basis and the main source of errors corresponds to the basis-set limitations. Furthermore we correct the energy by taking into account the core-core

Interactions and low energy collisions between an alkali ion and an alkali atom of different nucleus

“…A rather good agreement is observed for the equilibrium distance, however their potential is much deeper. Reasonably good agreement between our spectroscopic constant and those of Khelifi et al [58] is observed for the 2 2 Σ + and 3 2 Σ + states. The difference between Khelifi et al spectroscopic constants and our results are found to be 2.58% and 10.35% for R e and D e , respectively.…”

“…The spectroscopic constants of (LiCs) + and (NaCs) + , are presented respectively in tables 2 and 3 and compared with the available theoretical results [58,50]. To the best of our knowledge there is no experimental data for these ionic molecules.…”

“…To the best of our knowledge there is no experimental data for these ionic molecules. For the (LiCs) + ionic molecule, we compare our results only with the theoretical work of Khelifi et al [58] where they have used a similar method as used in our work. They reported for the ground state 1 2 Σ + the spectroscopic constants R e = 7.91 a.u.…”

Interactions and low-energy collisions between an alkali ion and an alkali atom of a different nucleus

“…The spectroscopic constants of (LiCs) + and (NaCs) + , are presented respectively in tables 4-4 and compared with the available theoretical results [50,58]. To the best of our knowledge there is no experimental data for these ionic molecules.…”

“…To the best of our knowledge there is no experimental data for these ionic molecules. For the (LiCs) + ionic molecule, we compare our results only with the theoretical work of Khelifi et al [58] where they used a similar method as used in our work. They reported for the ground state S + 1 2 the spectroscopic constants R e = 7.91 a.u.…”