The influence of temperature and pressure on the self-diffusion characteristics and mechanical sensitivity of DNTF: a molecular dynamics study

Abstract

Context

3,4-Bis(3-nitrofurazan-4-yl) furoxan (DNTF) is a typical low-melting-point, high-energy–density compound that can serve as a cast carrier explosive. Therefore, understanding the safety of DNTF under different casting processes is of great significance for its efficient application. This study employed molecular dynamics simulations to investigate the effects of temperature and pressure on the self-diffusion characteristics and mechanical sensitivity of DNTF. The analysis focused on the mean square displacement, self-diffusion coefficient, cohesive energy density, non-bonded energy, and critical bond length of DNTF under various temperatures (250 to 450 K) and pressures (0.1 to 10 MPa). The results indicate that the self-diffusion coefficient and mechanical sensitivity of DNTF are more sensitive to changes in temperature. As the temperature increases, the self-diffusion behavior of DNTF accelerates, making it more volatile. This effect is particularly notable within the temperature range of 350 to 400 K, where the growth rate of the self-diffusion coefficient is significantly faster than in the 250 to 350 K range. The trigger bond length (L_max) gradually increases with rising temperature, accurately reflecting the objective trend that mechanical sensitivity increases with temperature. The results of this study provide a theoretical basis for the application of DNTF in high-energy materials, particularly in enhancing its safety.

Methods

An 8 × 4 × 2 supercell model comprising 256 DNTF molecules was constructed in the Materials Studio 8.0 package. The DNTF supercell was geometrically relaxed using the conjugate gradient method. Subsequently, a 10-ps NPT molecular dynamics simulation was conducted on the supercell under conditions of 300 K and 0.1 MPa to relieve internal stresses, thereby obtaining DNTF crystals in the equilibrium state. NPT molecular dynamics simulations of the DNTF supercell were then carried out under the COMPASS force field at constant temperature. The temperatures were set to 250 K, 300 K, 350 K, 400 K, and 450 K, and the pressures were set to 0.1 MPa, 1 MPa, 3 MPa, 5 MPa, and 10 MPa. The total simulation time was 1000 ps with a time step of 1 fs. Every 1000 steps, information on mean square displacement, non-bonded energy, intermolecular forces, and critical bond length was recorded.