Ab initio potential energy surface and rovibrational states of HBO

The potential energy surface describing the large-amplitude motion of H aro und the BO core in the HBO molecule has been determined from ab initio calc ulations. This surface has been sampled by a set of 170 grid points from a two-dimensional space defined by the stretching and the bending coordinates of the H nucleus. At each grid point, the BO bond length has been optimize d using the second-order Moller-Plesset perturbation theory with the basis set aug-cc-pVTZ. The surface has a local minimum for the linear as well as the bent configuration of HBO. A low energy barrier to the linear configura tion BOH causes a large-amplitude motion and a strong rovibrational interac tion in the molecule. Its rovibrational dynamics is different from the dyna mics in bent or quasilinear triatomic molecules. (C) 1999 Elsevier Science B.V. All rights reserved.