Quantifying surface free energy of molecular crystal β-HMX using non-equilibrium molecular dynamics methods

Granular molecular crystals show a large variation in the orientation, length, shape, and cohesive interactions of interfaces when embedded polymer matrix. But determination associated excess free energy is not straightforward, especially due to entropic contribution which negligible for compounds. The surface (SFE) also important predict crystal shapes growth or prove crucial insights into mesoscale granular composites often with interfacial defects, voids, pores. In this paper, we use Molecular Dynamics (MD) assess adapt two non-equilibrium methods, namely, thermodynamic integration (NETI) modified steered MD (SMD), determine SFE various facets high-energy interest: β-HMX. Starting defect-free surfaces, both methods agree well experiment concerning most stable facets, whose further lowered by contribution. For some creation (debonding process) annihilation (bonding fundamentally different paths, henceforth irreversible. Then, discuss sources discrepancy between theoretical experimental SFE, considering non-reversible dissipative events, roughness, differences techniques. These can be applied wide range study interface stability polycrystals binding polymers, including effects defects.