Within the field of molecular simulation, the term “force field” refers to the mathematical model used to represent molecular interactions. This is true for atomic (all-atom) molecular dynamics and for coarse-grain (beaded) simulations in which groups of atoms are defined as a bead.
All-atom force fields provide atomic resolution and are helpful in elucidating molecular phenomena. However, the force fields can be fairly complex and too computationally expensive to simulate large systems. Coarse-grained force fields generally use a simplified interaction potential and have fewer interaction sites, as the atoms are amalgamated into beads. This reduces the computational expense and enables larger systems to be simulated at the expense of some of the finer detailed physics, which occurs at the atomic resolution.
We utilise both all-atom and a version of coarse graining called dissipative particle dynamics (DPD) force fields to perform molecular simulations. All-atom simulations have been used extensively across multiple fields for several decades. As a result, there are several force fields with good parameters, which have been tried and tested for a variety of systems. However, DPD is a relatively new method without standard force fields. We have therefore devised methods to parameterize a DPD force field automatically for a given application. Our methods optimize DPD force field parameters in reference to a user’s experimental data.
This work is being successfully applied to DPD simulations of micelle formation and partition coefficient (logP) predictions.