Changes In Energetic Properties Research Articles

External electric field induced conformational change and improved stability for series of energetic pentazole anion salts: A theoretical study

The structural features, energetic characteristics, and dynamics behaviors for series of pentazole anion salts under various intensities of external electric field (0.0–0.5 V/Å) were investigated by molecular dynamics simulations. The results show that there exist significant conformational changes for (NH4)N5 in 0.2 V/Å and [N(CH3)4]N5 in 0.5 V/Å. The sudden conformational changes resulted in sudden changes in energetic properties, dynamics behaviors, and so on. The comprehensive analysis on N-N bond length distribution, potential energy and cohesive energy density indicates that external electric field can improve thermodynamics stability. The analysis on diffusion behavior suggests that external electric field restrict the diffusion of N5− anion. Our studies innovatively introduced external electric field by Perl script and provide a new avenue to tune and improve the performances of energetic materials by external electric field.

Influence of Fluorination on Energetic Parameters of Silole, Phosphole, Thiophene, Oligomers of Silole and Related Acenes

The effects of fluorination on the energetic and thermochemical properties of a series of five-membered rings such as silole, phosphole and thiophene, and oligomers of silole and acenes were evaluated using density functional theory computations. Computed results indicate that substitution by fluorine atoms induces an increase of ionization energy and electron affinity and a decrease of proton affinity and HOMO-LUMO gap. For five-membered rings, fluorination effects are more significant on phosphole and silole as compared to those on thiophene. Changes in energetic properties of the oligomers of silole and acenes follow non-linear curves with increasing monomeric ring numbers. Effects of fluorination on energetic properties of the five-membered rings and oligomers are decreasing in the sequence of P-H > Si-H > C-H bonds. Replacement of H by F atom affects more strongly at Si-H bond than at C-H bond of siloles. Perfluorination of silole oligomers leads to derivatives with large electron affinity (> 4 eV). The anisotropy of induced current density (ACID) plots point out that fluorine replacement largely affects the electron delocalization at the C-C peripheral bonds in oligomers of silole and acenes. The silole unit emerges as a promising five-membered heterocycle to be used to tune up properties of oligomers.