Energetic molecule specific polarizable force field

The development of accurate force fields of energetic molecules (EM) to predict their crystal structures has been aggressively pursued in the EM research community. In this study, a non-empirical polarizable force field for energetic molecules is derived from the quantum-mechanical (QM) calculation results to well describe intermolecular interactions. We named this force field as the energetic molecule specific polarizable force field (EMS-PFF). It includes anisotropic atomic multipoles to describe the electrostatic interactions, atomic polarizability to consider the electron polarization, and standard MM2-type Buckingham dispersion-repulsion van der Waals interactions. Different from the traditional force fields by fitting some observed properties, EMS-PFF is parameterized only from the QM calculation results of energetic molecule at the MP2/6-311g(d,p) level. The QM-derived EMS-PFF is applied to optimize the 174 conversional CHNO energetic molecular crystals listed in the paper published in J. Phys. Chem. B 2004 108, 17730-17739. Our results demonstrate that EMS-PFF can better reproduce the experimental crystalline structures compared with the rigid optimization by the traditional isotropic charge-based Dreiding and COMPASS force fields. We believe that the non-empirical EMS-PFF can not only well predict the crystalline structures of the conversational CHNO energetic molecules, but also predict the crystal structures of other new high-nitrogen or full-nitrogen energetic materials.