First-Principles Study of Electronic, Absorption, and Thermodynamic Properties of Crystalline Styphnic Acid and Its Metal Salts

Abstract

The electronic structure, absorption spectra, and thermodynamic properties of crystalline styphnic acid and its metal salts (potassium, barium, and lead styphnates) have been studied using density functional theory within the local density approximation. The results show that the metal states affect the electronic structure of styphnic acid by modifying the density of states of the O atoms of hydroxyls. The C-O bond fission may be favorable in the decomposition of styphnic acid and its metal salts. The absorption spectra of the four crystals display a few strong bands in the fundamental absorption region. Compared with styphnic acid, potassium, barium, and lead styphnates decrease its enthalpy, entropy, free energy, and heat capacity as the temperature increases. However, the differences of the thermodynamic functions between each metal salt are very small. As the temperature increases, the decomposition reactions of the four crystals are more and more favorable thermodynamically. It is also found that there is a relationship between the band gap and impact sensitivity for the four crystals.

First-principles band gap criterion for impact sensitivity of energetic crystals: a review

“…Table 6 lists the band gaps of styphnic acid and its metal salts [33]. It is found that the band gap increases in the sequence of lead styphnate, potassium styphnate, barium styphnate, and styphnic acid.…”

“…Their results show that energy transfer rates have a good correlation with the impact sensitivity of explosives. Our recent first-principles studies on energetic inorganic and organic crystals [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] indicate that there is the relationship between the band gap and impact sensitivity.…”

First-principles study of energetic complexes (II): (5-cyanotetrazolato-N2) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues

“…The reaction mechanism for the complexes can be studied in terms of the interaction between HOMO and LUMO orbitals of the structure. Many studies have proved that the HOMO-LUMO energy gap is an important parameter characterizing the activity of energetic materials [25][26][27][28][29][30]. HOMO and LUMO 3D plots are shown in Fig.…”

Theoretical study of the correlation between electrostatic hazard and electronic structure for some typical primary explosives

“…Lead styphnate (1), lead azide (3), (5-cyanotetrazolato-N 2 ) pentaammine cobalt perchlorate (4), and tris(carbohydrazide) zinc perchlorate (5) are widely used primary explosives and hexa(1,5-diaminotetrazole) cobalt perchlorate (2) is a very promising initiator composition, so the structures and properties of these compounds have been studied in detail [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]; their chemical structures are shown in Fig. 1.…”