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Journal of Molecular Modeling

, Volume 19, Issue 9, pp 3893–3899 | Cite as

Molecular dynamics simulations of void defects in the energetic material HMX

  • Xiao Hui DuanEmail author
  • Wen Peng Li
  • Chong Hua Pei
  • Xiao Qing Zhou
Original Paper

Abstract

A molecular dynamics (MD) simulation was carried out to characterize the dynamic evolution of void defects in crystalline octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine (HMX). Different models were constructed with the same concentration of vacancies (10 %) to discuss the size effects of void. Energetic ground state properties were determined by annealing simulations. The void formation energy per molecule removed was found to be 55–63 kcal/mol−1, and the average binding energy per molecule was between 32 and 34 kcal/mol−1 according to the change in void size. Voids with larger size had lower formation energy. Local binding energies for molecules directly on the void surface decreased greatly compared to those in defect-free lattice, and then gradually increased until the distance away from the void surface was around 10 Å. Analysis of 1 ns MD simulations revealed that the larger the void size, the easier is void collapse. Mean square displacements (MSDs) showed that HMX molecules that had collapsed into void present liquid structure characteristics. Four unique low-energy conformers were found for HMX molecules in void: two whose conformational geometries corresponded closely to those found in HMX polymorphs and two, additional, lower energy conformers that were not seen in the crystalline phases. The ratio of different conformers changed with the simulated temperature, in that the ratio of α conformer increased with the increase in temperature.

Keywords

Void defect Dynamic evolution Molecular conformation 

Notes

Acknowledgments

The National Natural Science Foundation of China (No. 11176029) and the Key Research Project of Education Department of Sichuan Province (No. 10zd1106) are gratefully acknowledged for financial support.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Xiao Hui Duan
    • 1
    Email author
  • Wen Peng Li
    • 1
  • Chong Hua Pei
    • 1
  • Xiao Qing Zhou
    • 2
  1. 1.State Key Laboratory Cultivation Base for Nonmetal Composites and Functional MaterialsSouthwest University of Science and TechnologyMianyangPeople’s Republic of China
  2. 2.Institute of Chemical MaterialsChina Academy of Engineering PhysicsMianyangPeople’s Republic of China

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