Spectroscopic and electric properties of NaH and NaD: Extrapolation to the complete basis set limit

Abstract

We report accurate spectroscopic and electric properties for the ground electronic state of NaH and NaD from first principles electronic structure calculations at the coupled cluster singles-and-doubles with noniterative inclusion of connected triples [CCSD(T)] level of theory. A NaH/NaD Born–Oppenheimer potential energy curve is defined by extrapolating CCSD(T) ab initio energies to the complete basis set limit. Potential energy curves obtained using different basis sets and different basis set extrapolation schemes are compared to experimentally determined curves. When compared to experiment, basis set extrapolation yields a potential energy curve that results in highly accurate rotational and vibrational spectroscopic data for both NaH and NaD. An extensive set of spectroscopic parameters are tabulated. Electric properties are computed from CCSD(T) finite-field energies that have been extrapolated to the complete basis set limit. Dipole moment and dipole polarizability curves are reported. These quantities are vibrationally averaged for comparison with experimental values when they become available. Rovibrational transition matrix elements and vibrational lifetimes are also computed.