CALCULATION OF SOLVATION FREE ENERGIES OF AMINES

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When calculating binding free energies it is often essential to correctly calculate the solvation free energies of the subsystems which bind together. Our ability to predict solvation free enrgies can greatly affect the binding free energies calculated. Amines represent a good model to test our methods for solvation free energy evaluation, since their solvation is anomalous and hard to calculate. The aim of our project is to improve the calculations of solvation free energies of amines by developing better models of solvation. We design several models of amines using the most recent ab initio data and atomic polarizabilities. The free energies we calculated are improved compared to previous calculations, yet not in perfect agreement with experiment. We are trying to develop even better models by using different forms of the hydrogen bond interactions and also to develop simple models, which would yet give reasonable free energies. We used CGL molecular graphics to check the structure of the water box, the correct geometry of amine - water complexes and hydrogen bonds, and to check shrinking of amine bonds during free energy perturbation.