The force-field parameter fitting and application for (RDX, TATB)/Estane interfaces

Abstract High accuracy force-field parameters of (RDX, TATB)/Estane interfaces are fitted from the ab initio energy curves of various adsorption configurations, with rigorous validation using an independent test set. Employing this force-field in molecular dynamics (MD), we calculate a set of thermodynamic properties for plastic bonded explosives (PBXs), including the heat capacity, thermal expansion coefficient, bulk modulus, Grüneisen coefficient and Hugoniot parameters. Three critical dynamic behaviors are obtained: internal pressure, temperature-dependent debonding and elastic-plastic transition. First, the thermal expansion difference across interface generates internal pressure (0.6-0.8 GPa) for particles, which counteracts volume expansion. Second, the interfacial debonding occurs at 450 K for Estane-coated TATB and 400 K for Estane-coated RDX. Third, the tensile strain thresholds of void formation are quantified as 0.042 and 0.073 for Estane-coated TATB/RDX respectively, relevant to the elastic-plastic transition of material. The refined interfacial force-field demonstrates broad applicability in material design and property prediction, particularly for elucidating PBX failure mechanisms such as stress accumulation, defect evolution and debonding.