Parameterization of Crystalline Sulfamerazine for Coarse-Grained Molecular Dynamics

Abstract

Coarse-grained (CG) force fields for crystalline sulfamerazine (SMZ) including bond and non-bond parameters are presented in this study. Crystal structure and crystallization of SMZ are studied to understand tableting and dissolution kinetics especially interested in the pharmaceutical industry. In order to investigate the crystal structure of SMZ in phase Ⅱ , which is the most stable phase, coarse-graining method was applied to simplify molecular structure. A SMZ molecule was composed of 6 CG beads while considering that hydrogen bonding retains its crystal structure. Initial parameters were set by comparing the radial distribution functions (RDF) of the crystal structures of all-atom and CG models. Melting temperature and density of SMZ in liquid and solid states were compared with experimental values. The results showed 7 % error or less using established CG force fields. Finally, we showed the crystal growth on the crystalline slab, which exhibited the possibility of investigating the crystallization mechanism of other types of organic molecular crystal.