Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
December 19, 2012
VIP: MP2.5 and MP2.X: Approaching CCSD(T) Quality Description of Noncovalent Interaction at the Cost of Single CCSD Iteration
Robert Sedlak,* Kevin E. Riley, Jan Řezáč, Michal Pitoňák, and Pavel Hobza*
The accurate computational description of noncovalent interactions requires a high-order treatment of the electron correlation; it is known that MP2 does not yield reliable results. The next most efficient approach, MP3, is not better, but the results improve dramatically when the third-order contribution is scaled down. In the MP2.5 method, one half of the MP3 correlation energy is taken while in MP2.X, the scaling coefficient is optimized for each basis set used. We show that for a wide range of noncovalent complexes, these methods provide interaction energies and geometries with the same accuracy as higher-level and more computationally demanding methods.
Received October 11, 2012, published online January 11, 2013, DOI: 10.1002/cphc.201200850 – read now.