The dipole moment and molecular properties of CaH: A theoretical study

Abstract Failure of the CCSD(T) method in accurately reproducing the experimental dipole moment (2.94 Debye) of the calcium hydride is analyzed. Extrapolations to the complete basis set limit, core correlation, relativistic and vibrational contributions were considered. Our best theoretical result, 2.617 D, underestimates the experimental value by 11%. Other theoretical properties of CaH agree with experiment better. The bond length (1.9958 A), harmonic vibrational frequency (1298 cm −1 ), dissociation energy D e (1.845 eV), photodetachement electron affinity (0.947 eV), and the vertical ionization potential (5.686 eV) differ from experiment by 0.3%, 0.0%, 0.4%, 1.8% and 3.0%, respectively. The CCSD amplitudes and CASPT2 calculations indicate no quasidegeneracy.