Application of local second-order Møller-plesset perturbation theory to the study of structures in solution

Abstract

In this work, we discuss the use of local second order Moller-Plesset perturbation theory (LMP2) in combination with the COSMO continuum solvation model for obtaining optimized geometries of molecules in solution. Density-fitting approximations, which reduce the computational cost relative to the basis set size, are also applied. We present results for small molecular systems, which show the same pattern observed in gas phase calculations. LMP2 results are found to be in excellent agreement with the canonical method. The only difference noticed is a slight increase in the average bond lengths, which is linked to the implicit reduction of basis set superposition effects (BSSE). Applications in the geometry optimization of an arginine model interacting with anions in solution as well as to the conformers of oligo-beta-peptides are discussed.