Density Functional Theory Studies on Intermolecular Interactions of 4‐Amino‐3,5‐dinitropyrazole with NH3 and H2O

Abstract

AbstractDensity functional theory (DFT) method with 6‐311++G** basis set was applied to study intermolecular interactions of 4‐amino‐3,5‐dinitropyrazole (LLM‐116)/NH3 and LLM‐116/H2O supermolecules. Four optimized stable supermolecules were found on the potential energy surface. The intermolecular interaction energy was calculated with basis set superposition error (BSSE) correction and zero point energy (ZPE) correction. The greatest corrected intermolecular interaction energies of LLM‐116/NH3 and LLM‐116/H2O supermolecules are –42.75 and –19.09 kJ×mol‐1 respectively, indicating that the intensity of interaction between LLM‐116 and NH3 is stronger than that of LLM‐116/H2O. The intermolecular interaction is an exothermic process accompanied by a decrease in the probability of supermolecules formation, and the interactions become weak as temperature increase. Natural bond orbital (NBO) analysis was performed to reveal the origin of interaction. The IR spectra were obtained and assigned by vibrational analysis. Based on vibrational analysis, the changes of thermodynamic properties from LLM‐116 to supermolecules with temperature ranging from 200.0 to 400.0 K were obtained using statistical thermodynamic method.