Ab Initio Potential Energy Surface and Vibrational-Rotational Energy Levels of X2Σ+ CaOH

The equilibrium structure and potential energy surface of calcium monohydroxide in its ground doublet state, X2Σ+ CaOH, have been determined from large-scale ab initio calculations using the spin-restricted coupledcluster method, RCCSD(T), with basis sets of quadrupleand quintuple-ú quality. The vibrational-rotational energy levels of the CaOH and CaOD isotopomers were calculated using the variational method. The spectroscopic constants determined are found to be in remarkably good agreement with experimental data.