An optical scheme to create the simplest heteronuclear metal ultracold LiBe molecule is proposed based on ab initio quantum chemistry calculations. The potential energy curves, dipole moments, and transition dipole moments of $1{}^2\mathrm{\Sigma }^{+}, 2{}^2\mathrm{\Sigma }^{+}, 1{}^2\mathrm{\Pi }$, and $2{}^2\mathrm{\Pi }$ states are calculated using the multireference configuration interaction and large basis sets. The analytical functions deduced from the obtained curves are used to determine the rovibrational energy levels, the Franck-Condon factors, and the Einstein coefficients of the states through solving the Schrödinger equation of nuclear movement. The spectroscopic parameters are deduced with the obtained rovibrational energy levels. The Franck-Condon factors $(f_{00}:0.998, f_{11}:0.986, f_{22}:0.920)$ for the $2{}^2\mathrm{\Sigma }^{+}(v=0)\leftrightarrow 1{}^2\mathrm{\Sigma }^{+}(v^{\prime }=0)$ transition are highly diagonally distributed, and the calculated radiative lifetime (74.87 ns) of the $2{}^2\mathrm{\Sigma }^{+}$ state is found to be short enough for rapid laser cooling. The results demonstrate that LiBe could be a very promising candidate for laser cooling and a three-cycle laser cooling scheme for the molecule has been proposed.

• Received 27 June 2015

DOI:https://doi.org/10.1103/PhysRevA.92.032502