A new intermolecular potential energy surface for carbon dioxide from ab initio calculations

A new four-dimensional intermolecular potential energy surface for a carbon dioxide dimer on the basis of ab initio calculations is presented. One thousand and sixty energy points were calculated with the supermolecular approach on MP2 level of theory including full counterpoise correction. Application of different systematically extended basis sets up to [5s 4p 3d 2f 1g] allowed extrapolation to complete basis-set limit. The extrapolated energy points were fitted to a site-site potential function. The quality of the new potential was tested by computing values of the second virial coefficient over a wide range of temperatures. The results were compared with those from other recently published ab initio potential functions. The advantage of extrapolation to complete basis-set limit over the introduction of physically meaningless scaling parameters is discussed. (C) 2000 Published by Elsevier Science B.V. All rights reserved.