title: New ab initio potential energy surface and the vibration-rotation-tunneling levels of (H2O)2 and (D2O)2.
abstract: We report a new full-dimensional potential energy surface (PES) for the water dimer, based on fitting energies at roughly 30,000 configurations obtained with the coupled-cluster single and double, and perturbative treatment of triple excitations method using an augmented, correlation consistent, polarized triple zeta basis set. A global dipole moment surface based on Moller-Plesset perturbation theory results at these configurations is also reported. The PES is used in rigorous quantum calculations of intermolecular vibrational frequencies, tunneling splittings, and rotational constants for (H2O)2 and (D2O)2, using the rigid monomer approximation. Agreement with experiment is excellent and is at the highest level reported to date. The validity of this approximation is examined by comparing tunneling barriers within that model with those from fully relaxed calculations.
authors.affiliation: Cherry L. Emerson Center for Scientific Computation, Department of Chemistry, Emory University, Atlanta Georgia 30322, USA.
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: Bastiaan J
authors.initials: BJ
authors.lastname: Braams
authors.forename: Joel M
authors.initials: JM
authors.lastname: Bowman
authors.forename: Ross E A
authors.initials: RE
authors.lastname: Kelly
authors.forename: Jonathan
authors.initials: J
authors.lastname: Tennyson
authors.forename: Gerrit C
authors.initials: GC
authors.lastname: Groenenboom
authors.forename: Ad
authors.initials: A
authors.lastname: van der Avoird