Coarse-Grained Force Fields Built on Atomistic Force Fields

The coarse-grained force field (CGFF) bridges the gap between atomistic and mesoscopic simulations. We take a scale-up approach to build CGFF from all-atom force field (AAFF). Since AAFF is developed using the quantum mechanics data, this approach essentially makes CGFF on first principles. Using small molecules, alkanes, electrolyte solutions and polymers as examples, we discuss three factors that impact the development of CGFFs from AAFFs in this article: (1) The mapping rules balancing the computational efficiency and fidelity of representation are proposed to define bead types. (2) The analytic functions used in AAFFs with the atom types as interaction sites are used for CGFFs with the bead types as interaction sites. The analytic functional forms include temperature-dependent van der Waals (VDW) parameters and modified Lorentz-Berthelot combination rules. (3) A hybrid parametrization strategy combining bottom-up and top-down methods, which has been used for developing AAFFs from QMD, is used for developing CGFFs from AAFFs.