A molecular dynamics simulation study of buckyballs in water: atomistic versus coarse-grained models of C60.

A simple coarse-grained water-C(60) model potential is proposed to study the solvation behavior of C(60) in water. Extensive molecular dynamics simulations are performed to compare the hydration behavior of the coarse-grained C(60) with that of its atomistic counterpart. In the coarse-grained description, we model the C(60) as a spherical solute and its interaction with water is represented by a simple two-body central potential as obtained from a coarse graining of the interactions of a water molecule with all the atoms of the C(60). On the other hand, the atomistic model takes into account a discrete nature of all the atoms of C(60) explicitly. Molecular dynamics simulations are carried out in an isothermal-isobaric ensemble at normal temperature and pressure. Various spatial and orientational correlations of the water around the two model C(60)s are compared. The coarse-grained model is shown to reproduce the hydration behavior of the C(60) quite well. The simplicity and the computational economy of the coarse-grained model will allow for simulations of self-assembly processes of a much larger system over a longer period of time.