Theoretical investigation of vibrational and electronic properties of HMX crystal under uniaxial compression

Junyu Fan; Nan Gao; Pengju Wang

doi:10.1088/1361-648X/ac9a27

Theoretical investigation of vibrational and electronic properties of HMX crystal under uniaxial compression

J Phys Condens Matter. 2022 Oct 31;34(50). doi: 10.1088/1361-648X/ac9a27.

Authors

Junyu Fan^{1

2}, Nan Gao³, Pengju Wang⁴

Affiliations

¹ Department of Physics, Taiyuan Normal University, Jinzhong 030619, People's Republic of China.
² Institute of Computational and Applied Physics, Taiyuan Normal University, Jinzhong 030619, People's Republic of China.
³ School of Electronics and Information Engineering, Taizhou University, Taizhou 318000, People's Republic of China.
⁴ Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, People's Republic of China.

PMID: 36228627
DOI: 10.1088/1361-648X/ac9a27

Abstract

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is a typical energetic molecular crystal with excellent detonation performance and good thermal stability, has been widely used in military and civilian purposes. In this work, the vibrational properties of HMX combined with structure and electronic properties are studied to understand its pressure response against uniaxial compressions. The calculated eigenvalues of stress tensors show significant anisotropy of intermolecular interactions. Especially, the direction of shear stressτ_xyandτ_xzin [100] compression have an abrupt change nearV/V₀= 0.84. Further, Raman spectra under each uniaxial compression are simulated to inspect the molecular configuration of HMX. Compared to the blue shifts of [010] and [001] orientations, the discontinuous Raman shifts of atV/V₀= 0.86-0.84 in [100] orientation suggest that HMX would undergoes a possible structural transformation at the pressure of 6.82-9.15 GPa. Structural analysis implies that the subtle rotation of NO₂group is changed by intermolecular interactions of HMX. Moreover, the abnormal evolution of band gap is observed atV/V₀= 0.84 in [100] orientation, which is associated with the structure modification of HMX. Overall, the compression behaviors of HMX under uniaxial compressions would provide a useful insight for the actual shock compression conditions.

Keywords: electronic properties; energetic materials; first-principles calculations; uniaxial compression; vibrational properties.