Test study on the excitation spectra of the COH 2 van der Waals molecule

Abstract

In the present contribution we performed ab initio calculations within the supermolecule approach on the vertical excitation spectra of the diatomic van der Waals COH 2 molecule in its linear most stable OC…HH structure. They indicated the existence of at least one vibrational state in the ground CO( X 1∑ +)- H 2( X 1∑ g ) state, and of five vibrational states in the electronic CO( A 1 Π)- H 2( X 1∑ g ) excited configuration. Since ab initio correlation energy calculations for the excited electronic state are extremely demanding on computational resources, we are forced in practice to use medium-size highly optimized basis sets, suggesting to investigate the use of less demanding ab initio methods to represents the complete interaction energy surface of the excited states of interest.