Atoms-in-Molecules Study of Intra- and Intermolecular Bonding in the Pentaerythritol Tetranitrate Crystal

Abstract

Chemical bonding in the pentaerythritol tetranitrate crystal based on the experimental electron density obtained from X-ray diffraction data at 100 K and theoretical calculations at the experimental molecular geometry have been analyzed in terms of the Quantum Theory of Atoms in Molecules. Features of the intra- and intermolecular bond critical points and the oxygen atom lone-pair locations are discussed. Numerous intermolecular bonding interactions, including O...H and O...O, have been found and characterized. Atomic charges and atomic energies were integrated and compared with those for similar compounds. The N-O topological bond orders have been calculated for the first time, and the PETN atomic valences have been estimated.

Calculation and Measurement of Terahertz Active Normal Modes in Crystalline PETN

“…The tetragonal form PETN I is the crystal form studied herein. Two crystal cells are analysed in this work recorded at both room temperature [52] and 100 K. [53] PETN is an extremely powerful explosive with an explosive velocity of 8400 ms À1 [54] and is more sensitive to shock and friction than other explosives such as RDX and TNT. This means that its main use is in blasting caps and detonating chord, or as a booster, although it is found as a large constituent of some plastic explosives including Semtex and Metabel.…”

“…Furthermore, RT in Table 2 signifies the starting point of the optimisation was the unit cell recorded at room temperature [52] and this is the cell the optimised cell parameters are compared with. LT in Table 2 signifies that the starting point of the optimisation was the unit cell recorded at 100 K [53] and this is the cell the optimised cell parameters are compared with. Table 1.…”

“…Numbers in brackets are the estimated standard deviations. Experimental (RT) [52] Experimental (LT) [53] MM Optimised Percentage change [ [a] As optimisation calculations do not take temperature into account percentage changes are comparisons between optimised parameters and unit cell dimensions recorded at 100 K [53] The starting geometry for the four calculations was the unit cell recorded at room temperature.…”

Modeling solid–solid phase transitions in PETN using density functional theory

“…al. [11] invariably preserved the tetragonal symmetry of the initial structure, resulting in converged tetragonal structures at all pressures. The optimized lattice constants for hydrostatic pressures from 0 to 36 GPa are shown in Figure 1a.…”

“…Previous DFT calculations of crystalline PETN mostly focused on the tetragonal phase at ambient pressure [11,12] and under hydrostatic compression [13][14][15][16][17][18][19]. To our knowledge, no DFT calculations have described a stable orthorhombic phase of PETN.…”