Ab Initio Prediction of the Potential Energy Surface and Vibration−Rotation Energy Levels of CaCl₂

The equilibrium structure and potential energy surface of calcium dichloride (CaCl₂) have been determined from accurate ab initio calculations using the coupled-cluster method, CCSD(T), in conjunction with basis sets of quadruple- and quintuple-ζ quality. The CaCl₂ molecule was found to be linear at equilibrium. The vibration−rotation energy levels of various CaCl₂ isotopomers were predicted by the variational method. The calculated spectroscopic constants could be used to guide future high-resolution spectroscopic experiments on calcium dichloride.