Spectroscopically determined potential energy surfaces of the H216O, H217O, and H218O isotopologues of water

Adiabatic potential energy surfaces (PESs) for three major isotopologues of water, (H2O)-O-16, (H2O)-O-17, and (H2O)-O-18, are constructed by fitting to observed vibration-rotation energy levels of the system using the nuclear motion program DVR3D employing an exact kinetic energy operator. Extensive tests show that the mass-dependent ab initio surfaces due to Polyansky et al. [O.L. Polyansky, A.G. Csaszar S.V. Shirin, N.F. Zobov, P. Barletta, J. Tennyson, D.W. Schwenke, P.J. Knowles, Science 299 (2003) 539-542.] provide ail excellent starting point for the fits. The refinements are performed using a mass-in dependent morphing function, which smoothly distorts the original adiabatic ab initio PESs. The best overall fit is based oil 1788 experimental energy levels with the rotational quantum number J = 0, 2, and 5. It reproduces these levels with a standard deviation of 0.079 cm(-1) and gives, when explicit allowance is made for nonadiabatic rotational effects, excellent predictions for levels up to J = 40. Theoretical linelists for all three isotopologues of water involved in the PES construction were calculated up to 26 000 cm(-1) with energy levels Lip to J = 10. These linelists should make an excellent starting point for spectroscopic modelling and analysis. (C) 2006 Elsevier Inc. All rights reserved.