Notes on ab initio investigation of the CrH molecule and its interaction with He

Potential and dipole moment curves for the CrH(X$^6\Sigma^+$) molecule were obtained at the internally-contracted multi-reference configuration interaction with single and double excitations and Davidson correction (ic-MRCISD+Q) level using large basis set augmented with additional diffused functions and using Douglass-Kroll Hamiltonian for scalar relativistic effects. Also bound states, average positions and rotational constants calculated on the CrH(X$^6\Sigma^+$) potential are reported. The He-CrH(X$^6\Sigma^+$) potential energy surface was calculated with the coupled cluster singles, doubles, and noniterative triples [RCCSD(T)] method. The global minimum was found for the collinear He---Cr-H geometry with the well depth of 1143.84 cm$^{-1}$ at $R_e=4.15$ a$_0$. An insight in the character of the complex was gained by means of symmetry-adapted perturbation theory (SAPT) based on DFT description of the monomers. The presence of the so called "exchange cavity" was observed. Finally, bound states of the He-CrH complex for J = 0 are presented.