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An Ab Initio Molecular Dynamics study of Low Temperature Effects in Crystalline α‐HMX
Author(s) -
Zhu Simin,
Zhu Weihua
Publication year - 2019
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201900057
Subject(s) - delocalized electron , ab initio , crystal (programming language) , molecular dynamics , crystal structure , materials science , molecular vibration , chemistry , chemical physics , computational chemistry , crystallography , molecule , organic chemistry , computer science , programming language
Ab initio molecular dynamics and DFT‐D method were used to study the average structural, electronic, vibrational frequencies, optical properties, and mechanic properties of the α‐HMX (octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) crystal at different temperatures. The calculated crystal structure agrees well with experimental results at ambient temperature. The increasing temperature does not produce any obvious effects on the crystal structure of α‐HMX. But the increasing temperature strengthens the free rotation of the nitro groups. As the temperature increases, the electrons become more and more delocalized. The NO 2 asymmetric stretching modes are sensitive to the temperature. The vibrational modes of these side groups (NO 2 and CH 2 ) couple strongly with the increasing temperature and so could provide an important vibrational channel for H migration reactions and N‐NO 2 cleavage. The effects of temperature on the optical properties of the α‐HMX crystal are different in different frequency regions. This finding indicates that the increasing temperature produces a complicated effect on the mechanical properties of the α‐HMX crystal.