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arXiv:2003.12051 · Physical Review A

Ab initioproperties of the NaLi molecule in the a3Σ+ electronic state

Marcin Gronowski, Adam M. Koza, Michał Tomza

Published Aug 10, 2020• 28 citations
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Abstract

Ultracold polar and magnetic $^{23}\mathrm{Na}^{6}\mathrm{Li}$ molecules in the rovibrational ground state of the lowest triplet ${a}^{3}{\mathrm{\ensuremath{\Sigma}}}^{+}$ electronic state have been recently produced. Here, we calculate the electronic and rovibrational structure of these 14-electron molecules with spectroscopic accuracy ($<0.5\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$) using state-of-the-art ab initio methods of quantum chemistry. We employ the hierarchy of the coupled-cluster wave functions and Gaussian basis sets extrapolated to the complete basis set limit. We show that the inclusion of higher-level excitations, core-electron correlation, relativistic, QED, and adiabatic corrections is necessary to accurately reproduce scattering and spectroscopic properties of alkali-metal systems. We obtain the well depth, ${D}_{e}=229.9(5)\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, the dissociation energy, ${D}_{0}=208.2(5)\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, and the scattering length, ${a}_{s}=\ensuremath{-}{84}_{\ensuremath{-}41}^{+25}\phantom{\rule{4pt}{0ex}}\mathrm{bohr}$, in good agreement with recent experimental measurements. We predict the permanent electric dipole moment in the rovibrational ground state, ${d}_{0}=0.167$(1) D. These values are obtained without any adjustment to experimental data, showing that quantum chemistry methods are capable of predicting scattering properties of many-electron systems, provided relatively weak interaction and small reduced mass of the system.

DOI
10.1103/physreva.102.020801

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