Theoretical study of the phonon-phonon scattering mechanism and the thermal conductive coefficients for energetic material

The elastic constants and force constants of an energetic material named as 1,3,5-triamino- 2,4,6-trinitrobenzene (TATB) are calculated by first-principles method under the GGA+vdW functional. Based on them, a physical picture to describe the phonon-phonon scattering mechanism is obtained, and a method to evaluate the thermal conductive tensor is developed. The resulting thermal conductivities are in agreement with the available experiments. We find that 20 vibrational modes play important roles in determining the heat exchange process of TATB. The vibrational direction, symmetry, displacement field and the detailed information of the key vibrational modes are obtained.