title: Fourfold Clusters of Rovibrational Energies in H2Po Studied with an ab Initio Potential Energy Function
abstract: We report here an ab initio investigation of the cluster effect (i.e., the formation of four-member groups of nearly degenerate rotation-vibration energy levels at higher J and Ka values) in the H2Po molecule. The potential energy function has been calculated ab initio for a total of 143 molecular geometries by means of the CCSD(T) method, using an averaged relativistic effective potential for Po in conjunction with a newly optimized basis set. The values of the potential energy function obtained cover the region up to around 5000 cm-1 above the equilibrium energy. On the basis of the ab initio potential, the rotation-vibration energies of H2209Po have been calculated with the MORBID (Morse oscillator rigid bender internal dynamics) Hamiltonian and computer program. In particular, we have calculated the rotational energy manifolds for J </= 40 in the vibrational ground state. We find that the formation of fourfold clusters in H2Po is very similar to that in H2Te. Copyright 1997 Academic Press. Copyright 1997Academic Press
authors.affiliation: Facultad Quimica, U. Complutense de Madrid, Madrid, E-28040, Spain
authors.initials: PC
authors.lastname: Gomez
authors.initials: LF
authors.lastname: Pacios
authors.initials: P
authors.lastname: Jensen