Periodic DFT study of structural transformations of cocrystal NTO/TZTN under high pressure

Theoretical study on the structure, electronic properties, intermolecular interactions, and detonation performance of DAF:ADNP co-crystal

CONTEXT

Explosives have a wide range of applications in many fields due to their high energy and high density. Recently, a new synthesized co-crystal explosive DAF:ADNP presents high detonation performance and low sensitivity. This work is aimed to understand how the structure and intermolecular interactions affect the performance of the DAF:ADNP co-crystal. The results indicate that the formed π-π interactions and stronger hydrogen bonds in the co-crystal enhance its stability and its impact sensitivity is reduced. The strong intralayer H···N and H···O interactions and interlayer π-π stacking are the main driving force for the formation of the co-crystal. Compared with the pure crystals, the detonation performance of the co-crystal slightly decreases, while its sensitivity reduces.

METHODS

All calculations were used the DFT-PBE-D method with Vanderbilt-type ultrasoft pseudopotentials and plane wave (340.0 eV) in the CASTEP package. Radial distribution function were calculated by NVT-MD simulations for 100 ps with a time step of 1 fs at 298 K. Hirshfeld surfaces were generated by CrystalExplorer 3.0 and reduced density gradient analyses were performed by Multiwfn 3.0.

The modulation effect of electron-rich solvents on the supramolecular networks and photochromic properties of naphthalene diimide molecules

The electron-rich solvents can effectively regulate the interfacial contacts of electron donors/acceptors and the photochromic properties of naphthalene diimide molecules.

Theoretical Insights on the High Pressure Behavior of Pentazolate Anion Complex [Co(H2O)4(N5)2]·4H2O

Periodic dispersion corrected density functional theory (DFT) calculations were carried out to examine the Hirshfeld surface, two dimensional (2D) fingerprint plots, crystal structure, molecular structure and density of state of all-nitrogen pentazolate anion complex [Co(H2O)4(N5)2]·4H2O under hydrostatic pressure from 0 to 20 GPa. The GGA/PW91-OBS method was applied in the present study. The intercontacts in [Co(H2O)4(N5)2]·4H2O were analyzed by Hirshfeld surfaces and 2D fingerprint plots. With ascending pressure, the lattice constants, compression rates, bond lengths, bond angles, and density of states change irregularly. Under 11.5, 13.0 and 15.8 GPa, covalent interaction competition is obvious between Co-N and Co-O bonds. It is possible to achieve orderly modification and regulation of the internal structure of [Co(H2O)4(N5)2]·4H2O by applied pressure. This is in accordance with the results from density of states analysis. The external compression causes the nonuniformity of electron density and the differential covalent interaction between pentazolate anion, coordinated water and atom Co. It is of great significance to interpret inter/intramolecular interaction and structural stability of [Co(H2O)4(N5)2]·4H2O and provide theoretical guidance for the design of metal complexes of all-nitrogen pentazolate anion.

Dissociative adsorption modes of TATB on the Al (111) surface: a DFT investigation

Herein, the adsorption modes and electronic structures of TATB/Al (111) systems were investigated using the density functional theory (DFT) approach. We found that chemical adsorption led to the decomposition of the TATB molecule on the Al surface by four adsorption modes. All the adsorption configurations were accompanied by fractures of the N-O bonds in the nitro groups. In addition, there was a hydrogen atom transfer for 5P. For parallel and vertical adsorptions, the TATB molecules favored planar or quasi-planar structures. The order of total energy with BSSE correction matches well with the order of adsorption energy. The absolute values of energy and adsorption energy of 6P and 6V are highest in the parallel and vertical adsorption systems, respectively. Electrons are transferred from the Al (111) surface to the TATB molecule; this results in the activation of TATB on the Al (111) surface and obvious augmentation of the PDOS (partial density of states) peaks of the N and O atoms. From the Al (111) surface to the TATB molecule, the transfer of the electrons of 4P (14.00e) and 6V (9.04e) is largest for the parallel and vertical adsorptions, respectively.