Coarse-grained force fields via rotational entropy corrections to free-energy landscapes of diffusing molecules

The construction of accurate interatomic potentials, and related fields of forces, from equilibrium conformational distributions of molecules is a crucial step in coarse-grained modeling. In this work we show that in order to develop accurate laboratory-frame force fields that preserve translational and rotational diffusion of a molecule, the observed body-fixed free-energy landscape must be corrected for conformation-dependent rotational entropy to isolate the potential energy surface. We further demonstrate that even when the instantaneous effects of the correction are small, the resulting lagged correlations of the modeled force can be greatly altered and hence the correction is especially vital when parametrizing friction coefficients using modeled interatomic potentials.