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ORIGINAL PAPER

The influence of temperature and component proportion on stability, sensitivity, and mechanical properties of LLM-105/HMX co-crystals via molecular dynamics simulation Ming-yao Li 1,2 & Liang-fei Bai 2 & Ye-bai Shi 2,3 & Guang-ai Sun 2 & Feng Wang 1 & Jian Gong 2 & Xin Ju 3 Received: 1 December 2019 / Accepted: 23 February 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Based on molecular dynamics (MD) simulation, the binding energy, cohesive energy density (CED), bond length, and mechanical parameters were calculated for 2,6-diamino-3,5-dinitropyrazine-l-oxide (LLM-105) crystal, octahydro-1,3,5,7-tetranitro1,3,5,7-tetrazocine (HMX) crystal, and their co-crystals under different temperatures. Three LLM-105/HMX patterns were constructed to investigate the influence of component proportion on structures and properties of co-crystals, in which the mole ratios of LLM-105 and HMX are 1:1, 1:2, and 2:1. The effect of temperature and components on the stability and sensitivity were investigated as well. The results show that the binding energies, CED and mechanical parameters of all the co-crystals, decrease when the temperature increases from 248 to 398 K, while their maximum N–NO2 bond length (Lmax) increases with rising temperature, indicating that the sensitivities increase and stabilities decrease when temperature rises. At all temperatures, cocrystals exhibit larger CED and shorter bond length than that of single explosive, demonstrating that they are more stable and less sensitive than single crystal, where the stability of co-crystals was ordered as 2:1>1:1>1:2. Moreover, the bulk modulus (K) and shear modulus (G) of co-crystals are lower than that of HMX, conversely, the Cauchy pressure and K/G are higher than that of HMX, implying co-crystals have better ductility. Finally, the 2:1 ratio of LLM-105/HMX co-crystal was identified as the excellent one, owning to the highest binding energy, highest CED, shortest Lmax, and greatest ductility.

Keywords HMX/LLM-105 co-crystal . Molecular dynamics(MD) simulation . Bindingenergy . CED . Bond length . Mechanical properties

Introduction

Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00894-020-4329-4) contains supplementary material, which is available to authorized users. * Feng Wang [email protected] Xin Ju [email protected] 1

School of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074, China

2

Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621999, China

3

School of Physics, University of Science and Technology Beijing, Beijing 100871, China

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is one of the military standard high energy density materials (HEDMs). It has been widely used in polymer-bonded explosives (PBX), propellants, and other explosives due to the excellent properties, for instance, high energy density, high detonation velocity, and high explosion pressure. However, compa