Accurate global ab initio potentials at low-cost by correlation scaling and extrapolation to the one-electron basis set limit

A recently proposed scheme that enables a potential energy surface corresponding to a calculation with a large target basis set to be obtained from small basis set calculations via scaling of the electron correlation at a single-pivotal geometry is generalized to include an arbitrary number of such geometries. If the correlation is extrapolated to the complete basis set limit at the pivotal geometries and used for the scaling, the method can yield accurate potentials at costs up to factors nearly fifty times cheaper than required otherwise. The approach, free from parameters alien to the ab initio methods, is tested on N-2, O-2, and F-2. (c) 2007 Elsevier B.V. All rights reserved.