The potential energy surface and the highly excited vibrational band origins of the water molecule

The potential energy surface for the electronic ground state of the water molecule is optimized by means of a variational procedure using the exact vibrational Hamiltonian in the bond length-bond angle coordinates. In the optimization, Jensenʹs potential energy function (J. Mol. Spectry. 133 (1989) 438) is taken as the starting point andthe recently observed band origins below 22000 cm−1 given by Rothman and co-workers (J. Quantum Spectry. Radiative Transfer 48 (1992) 469) are involved. The standard deviation of this fitting for the 70 vibrational levels is 1.171 cm−1.