Implementation and application of a GCOSMO solvation model within DeFT and a hybrid DeFTMopac Monte Carlo algorithm

Abstract

A Generalized COnductor-Like Solvation MOdel (GCOSMO) was implemented within our own Density Functional Theory software, DeFT, combined with a Solvent Interaction Potential (SIP) algorithm to assign the atomic radii. The SIP radii were tested against a set of fixed radii from the literature. We concluded that the SIP radii outperform the fixed radii. We successfully reproduced the solvation of glycine and the tautomerization of 2-hydroxypyridine/2-pyridone in solution with our GCOSMO/SIP approach. A hybrid DeFT/Mopac Monte Carlo (MC) algorithm was also implemented. The algorithm differs from purely ab initio MC by inserting a secondary semi-empirical MC chain between each ab initio configuration of the main chain. This leads to a reduction of the correlation between the configurations and a more efficient sampling of the potential energy surface. Two reactions were studied: the conrotatory ring opening of cyclobutene and the Diels-Alder reaction of ethylene and butadiene to form cyclohexene.