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Vibrational and thermodynamic properties of β-HMX: A first-principles investigation
- Source :
- The Journal of Chemical Physics. 134:204509
- Publication Year :
- 2011
- Publisher :
- AIP Publishing, 2011.
-
Abstract
- Thermodynamic properties of β-HMX crystal are investigated using the quasi-harmonic approximation and density functional theory within the local density approximation (LDA), generalized gradient approximation (GGA), and GGA + empirical van der Waals (vdW) correction. It is found that GGA well describes the thermal expansion coefficient and heat capacity but fails to produce correct bulk modulus and equilibrium volume. The vdW correction improves the bulk modulus and volume, but worsens the thermal expansion coefficient and heat capacity. In contrast, LDA describes all thermodynamic properties with reasonable accuracy, and overall is a good exchange-correlation functional for β-HMX molecular crystal. The results also demonstrate significant contributions of phonons to the equation of state. The static calculation of equilibrium volume for β-HMX differs from the room-temperature value incorporating lattice vibrations by over 5%. Therefore, for molecular crystals, it is essential to include phonon contributions when calculated equation of state is compared with experimental data at ambient condition.
- Subjects :
- Equation of state
Bulk modulus
Condensed matter physics
Chemistry
General Physics and Astronomy
Thermodynamics
Heat capacity
Thermal expansion
Condensed Matter::Materials Science
symbols.namesake
symbols
Density functional theory
Physical and Theoretical Chemistry
Local-density approximation
van der Waals force
Elastic modulus
Subjects
Details
- ISSN :
- 10897690 and 00219606
- Volume :
- 134
- Database :
- OpenAIRE
- Journal :
- The Journal of Chemical Physics
- Accession number :
- edsair.doi.dedup.....3d83833d925e714e22adec6799004a86
- Full Text :
- https://doi.org/10.1063/1.3587135