All-atom simulation and excess properties study on intermolecular interactions of amide-water system

All-atom models have been adopted for molecular dynamics simulation. The excess relative extant of hydrogen bond ηrelE in MD simulation is introduced to describe the anomalous non-ideal behaviors of amide-water mixtures. Interestingly, the ηrelE calculated by the MD simulations in the amide aqueous solutions shows the largest deviation at xamide ≈ 0.33 which presents excellent agreement with the excess enthalpy in the concentration dependence. The hydrogen bond of CO⋯HWOW might play a role of bridge between the self-associate clusters of amide and water. It is very likely that the stable configuration of (Amide)m·CO⋯HWOW·(H2O)n leads to the largest deviation of ηrelE and excess enthalpy observing at xamide ≈ 0.33.