skip to main content

SciTech ConnectSciTech Connect

Title: Characteristics of energy exchange between inter- and intramolecular degrees of freedom in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with implications for coarse-grained simulations of shock waves in polyatomic molecular crystals

In this report, we characterize the kinetics and dynamics of energy exchange between intramolecular and intermolecular degrees of freedom (DoF) in crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). All-atom molecular dynamics (MD) simulations are used to obtain predictions for relaxation from certain limiting initial distributions of energy between the intra- and intermolecular DoF. The results are used to parameterize a coarse-grained Dissipative Particle Dynamics at constant Energy (DPDE) model for TATB. Each TATB molecule in the DPDE model is represented as an all-atom, rigid-molecule mesoparticle, with explicit external (molecular translational and rotational) DoF and coarse-grained implicit internal (vibrational) DoF. In addition to conserving linear and angular momentum, the DPDE equations of motion conserve the total system energy provided that particles can exchange energy between their external and internal DoF. The internal temperature of a TATB molecule is calculated using an internal equation of state, which we develop here, and the temperatures of the external and internal DoF are coupled using a fluctuation-dissipation relation. The DPDE force expression requires specification of the input parameter σ that determines the rate at which energy is exchanged between external and internal DoF. We adjusted σ based on the predictions for relaxation processes obtained from MD simulations. The parameterizedmore » DPDE model was employed in large-scale simulations of shock compression of TATB. We show that the rate of energy exchange governed by σ can significantly influence the transient behavior of the system behind the shock.« less
Authors:
;  [1] ;  [2]
  1. Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600 (United States)
  2. CEA, DAM, DIF, F-91297 Arpajon (France)
Publication Date:
OSTI Identifier:
22493734
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 6; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANGULAR MOMENTUM; ATOMS; CHEMICAL REACTION KINETICS; COMPRESSION; DEGREES OF FREEDOM; ENERGY TRANSFER; EQUATIONS OF MOTION; EQUATIONS OF STATE; FLUCTUATIONS; MOLECULAR CRYSTALS; MOLECULAR DYNAMICS METHOD; MOLECULES; SHOCK WAVES; TATB; TRANSIENTS