Comparison of the water perturbations induced by two small organic solutes: ab initio calculations and molecular dynamics simulation

Quantum mechanical ab initio calculations have been performed to evaluate the optimized geometry of trimethy1amine-N-oxide (TMAO) and t-butyl alcohol (TBA) and their interaction potentials with water. The latter have been used in extensive molecular dynamics simulations. Statistical analyses of the systems configurations suggest that the water molecules involved in hydration are more tightly coordinated by TMAO than by TBA. This affects the diffusion properties of the solutes and of the surrounding water molecules.