Energy change mechanisms of HMX solute molecules in pure solvents and binary solvent mixtures

Abstract

The quantum mechanical continuum solvation models have been used to probe into the energy change mechanisms of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) solute molecules in pure solvents and binary solvent mixtures. The relation between the long-range electrostatic energy and the static dielectric constant is determined by the integral equation-formalism polarizable continuum model (IEFPCM). For solvents having hydrogen bonds, the electrostatic interaction is significantly high due to the short-range polarization induced by solute-solvent hydrogen bonding that is unfavorable to crystallization from solution. The non-electrostatic energy has been calculated by the universal solvation model (SMD), which arises from the effects of cavitation, dispersion, and solvent structure (CDS). The calculated interaction energies from different components are discussed in terms of the solvent descriptors, temperature and molecular geometries. The simulation results show that the effects of CDS are important to antisolvent crystallization in dimethyl sulfoxide (DMSO)-alcohol binary solvent mixtures and the energy change mainly originates from the short-range non-electrostatic interaction.