Accurate ab initio calculations of spectroscopic constants and properties of BeLi+

Abstract

We have calculated the ground state spectroscopic constants and the molecular properties, of a molecular ion BeLi + , such as dipole moment, quadrupole moment and dipole polarizability at different levels of correlation: many-body perturbation theory (MP2), coupled cluster method with single and double excitations (CCSD) and CCSD with perturbative triples (CCSD(T)). The correlation consistent polarized valence cc-pVXZ (X=D, T, Q) basis sets and also their augmented counterparts are used together with the non-relativistic and relativistic Hamiltonians. The results are extrapolated to the complete basis set limit (CBS) using exponential-Gaussian function. Thus, accurate and reliable results for BeLi + with the most conservative error estimates on them are reported.

Calculations of electronic properties and vibrational parameters of alkaline-earth lithides: MgLi+ and CaLi+

“…The behaviour of quadrupole moment and dipole polarizability curve is similar to that observed for BeLi + ion in Ref. [47]. Our recommended values of the results obtained at the highest level of correlation, i.e., CCSD(T) and with the largest basis sets, i.e., QZ, are highlighted, together with the error bars, in bold fonts at the bot- tom of Table III and they could serve as benchmarks for other calculations in future and also they may be useful for experimentalists who would consider working on these molecular systems in future.…”

“…Furthermore, we have extended this work to the lower excited states for both the molecular ions using equation-of-motion CCSD (EOM-CCSD) method. The current work is a sequel to our previous paper on BeLi + [47]. The paper is presented in three other sections: the introduction is followed by a brief description of the methods involved in Section II, the detailed description of the results in Section III and finally the summary of the present work in Section IV.…”

Electronic Spectroscopy and Photoionization of LiBe

“…For v′ = 0, they obtained values of 78 and 75 ns, respectively. The present measurement gives a value of 60 (20) ns, where the large error bars reflect the poor signal-to-noise ratio of the pump−probe measurements. We note that the predicted lifetime is within the 1σ error range.…”

“…Subsequent theoretical calculations for LiBe have predicted properties for the ground state and a range of electronically excited states. − A subset of this work has been motivated by the potential for cooling LiBe or the LiBe + cation to ultracold temperatures. ,,− From this perspective, the attractive attributes of LiBe­(X) for ultracold molecule studies include a large dipole moment (predicted to be 3.5 D , ) and the magnetic moment associated with the unpaired electron. You et al examined the possibilities for direct laser cooling of LiBe.…”

“…Theory predicts a binding energy that is approximately a factor of 2 greater than that of neutral LiBe(X), with a permanent dipole moment (3.55 D) that is almost unchanged by ionization. 17,18,20 Cold LiBe + could be generated by at least two paths. The first, dependent on verification that laser cooling of LiBe is feasible, would involve the photoionization of cold LiBe.…”