Moller-Plesset perturbation theory gradient in the generalized hybrid orbital quantum mechanical and molecular mechanical method

An analytic gradient expression is formulated and implemented for the second-order Moller-Plesset perturbation theory (MP2) based on the generalized hybrid orbital QM/MM method. The method enables us to obtain an accurate geometry at a reasonable computational cost. The performance of the method is assessed for various isomers of alanine dipepetide. We also compare the optimized structures of fumaramide-derived [2]rotaxane and cAMP-dependent protein kinase with experiment. (C) 2010 American Institute of Physics. [doi:10.1063/1.3329370]