Verification of the Accuracy and Efficiency of Dispersion-Corrected Density Functional Theory Methods to Describe the Lattice Structure and Energy of Energetic Cocrystals

Abstract

Energetic cocrystals (ECCs), as a promising alternative to new energetic materials, are attracting increasing attention. However, it is a challenge to accurately describe their structural and energetic properties using quantum chemistry approaches. In this work, 13 dispersion-corrected density function theory potentials, as well as the original PBE functional, are adopted to evaluate their accuracy and efficiency in describing the lattice parameters and lattice energy of 53 ECCs. These ECCs are classified into three categories in terms of the characteristics of intermolecular interactions therein; that is, C-ECCs, T-ECCs, and H-ECCs feature common weak intermolecular interaction, π-stacking, and rather strong hydrogen bonds (HBs), respectively. Generally, PBE-D3(0), PBE-D3­(BJ), PBE-TS, PBE-TS­(HI), optPBE-vdW, and vdW-DF2 methods provide good description of lattice parameters for all the ECCs, and the accuracy of these methods is somewhat dependent on the type of ECCs; that is, optPBE-vdW, optPBE-vdW, and PBE-D3­(BJ) methods are the best for C-ECCs, T-ECCs, and H-ECCs, respectively. In contrast, PBE-D3­(BJ) is the most reliable for lattice energy prediction among the six most accurate potentials for describing lattice parameters. Accounting for both the accuracy and time consumption, PBE-D2, PBE-D3(0), and PBE-D3­(BJ) methods are recommended for the ECCs dominated by common weak interactions, π-stacking, and rather strong HBs, respectively. This work provides guidelines to select appropriate methods for describing energetic molecular crystals.

Energetics and Ionic–Electronic and Geometric Variabilities of Hydroxylammonium-Based Salts

“…We first identify the feasibility of the dispersion-correction method, PBE-D3­(BJ), to the concerned HA + -based EISs. As listed in Table S1 of the Supporting Information, the comparison of cell volumes from the PBE-D3­(BJ) optimization and experimental determination verifies the reliability of PBE-D3­(BJ) as expected, with a mean relative deviation (MRD) of 1.26% and a maximal relative deviation (RD max ) of 2.5%, close to those of energetic cocrystals composed of neutral molecules . In fact, PBE-D3­(BJ) was identified as suitable to the energetic cocrystals consolidated by rather strong intermolecular HBs .…”

“…As listed in Table 2, the CED of HA + -based EISs ranges from 4.80 to 12.7 kJ/cm 3 , much higher than those of energetic cocrystals within 0.80−1.72 kJ/cm 3 . 52 This reflects the higher strength of the interionic interactions relative to the intermolecular interactions.…”

“…As listed in Table S1 of the Supporting Information, the comparison of cell volumes from the PBE-D3(BJ) optimization and experimental determination verifies the reliability of PBE-D3(BJ) as expected, with a mean relative deviation (MRD) of 1.26% and a maximal relative deviation (RD max ) of 2.5%, close to those of energetic cocrystals composed of neutral molecules. 52 In fact, PBE-D3(BJ) was identified as suitable to the energetic cocrystals consolidated by rather strong intermolecular HBs. 52 Thus, the validation of PBE-D3(BJ) to these HA + -based EISs is reasonable as they consist of the same C, H, N, and O atoms and similar intermolecular HBs to the energetic cocrystals.…”

“…52 In fact, PBE-D3(BJ) was identified as suitable to the energetic cocrystals consolidated by rather strong intermolecular HBs. 52 Thus, the validation of PBE-D3(BJ) to these HA + -based EISs is reasonable as they consist of the same C, H, N, and O atoms and similar intermolecular HBs to the energetic cocrystals.…”

“…Previous work has ascertained that the intermolecular interactions in EISs usually feature stronger HBs than those in common energetic compounds . Thus, GGA-PBE with the D3­(BJ) dispersion-correction method , that was validated to HB-containing systems recently was employed to relax lattice structures and calculate the formation energy and LE. All of the structure optimizations were implemented by VASP.5.4.4 with PAW pseudopotentials .…”