Theoretical Approach to Predict Crystal Densities of Organic and High Energy Density Molecules

초록

Crystal density is one of the fundamental properties of organic molecules. In our research on developing new high energy density molecules (HEDM), it is the key input parameter for obtaining performance data using Cheetah 2.0 program. In earlier works1,2, group additivity method (GAM) was used to estimate solid density of HEDM. In GAM, the volumes or densities of various functional groups were evaluated from the X-ray structures of HEDM and the final densities were the sum of the contribution from the constituent functional groups. In MSEP method, however, the solid density was calculated from the statistical descriptors derived from the electrostatic potential (ESP) values on the van der Waals surfaces of molecules.3 These approaches are, however, too complicated to apply or require high computational work for practical application. In this work, we developed 11 correction terms after minimizing the errors between experimental and gas-phase molecular densities. The training set contains 75 organic and HEDM. The correlation coefficient is ca. 0.98 regardless of computational methods employed in the geometry optimization procedure. This new approach is fast and reliable and thus can be adapted to a virtual screening tool for designing new HEDM.