Theoretical analysis on the structural, electronic, and intermolecular interaction features of the CL20/1-AMTN cocrystal.

CONTEXT: The cocrystal strategy is an effective approach to reducing the sensitivity of high-energy CL-20 while maintaining its superior detonation performance. However, the microscopic mechanism by which guest molecules stabilize the host lattice remains insufficiently understood. Using density functional theory (DFT) and molecular dynamics (MD) simulations, we compare the the geometric structures and electronic properties, SAPT analysis, Hirshfeld surfaces, and radial distribution functions of the CL-20/1-amino-3-methyl-1,2,3-triazolium nitrate (1-AMTN) cocrystal with those of pure CL-20. The results show that 1-AMTN introduction increases the total density of states (DOS), and significantly reduces the band gap from 3.251 eV to 2.222 eV. Although a narrower band gap is generally correlated with higher electronic excitation sensitivity, further SAPT, Hirshfeld surface, and RDF analyses reveal that the cocrystal exhibits strengthened O-H…O hydrogen-bond networks and denser van der Waals contacts. Quantitative Hirshfeld analysis shows that the combined O…H/H…O polar contacts exceed 59% in the cocrystal, accompanied by newly emerged N…H interactions. Energy decomposition indicates that electrostatic and dispersion forces cooperatively dominate the lattice stabilization. Collectively, 1-AMTN enhances the supramolecular non-covalent interactions, providing additional binding energy that likely counterbalances the electronic sensitivity risk, which serves as the microscopic origin of the experimentally observed desensitization. This work elucidates the essential role of guest molecules in cocrystal stabilization and provides theoretical guidance for the rational design of low-sensitivity, high-energy cocrystals.

METHODS: DFT calculations were performed using the CASTEP software package with the PBE functional and Grimme DFT-D2 dispersion correction, using a 750 eV cutoff energy and a 1 × 1 × 1 Monkhorst-Pack k-point grid. Molecular dynamics simulations were conducted using Materials Studio with the COMPASS force field under NPT ensemble at 298 K for 200 ps (0.5 fs time step). SAPT(DFT) analysis was performed using PSI4 at the SAPT0 level with the aug-cc-pVDZ basis set and counterpoise BSSE correction. Hirshfeld surface analysis was carried out using CrystalExplorer 17.0.