Molecular Design and Properties Prediction of Cyclotetramethylene Tetranitramine (HMX) Derivatives with Amido Groups
B. Tan, R. Peng, H. Li, B. Jin, S. Chu, X. Long
Keywords: octogen, bond dissociation energy, enthalpy of formation, bond order
Pages: 644-649
Abstract
DFT/BLYP/DNP method was employed to calculate the total energy of cyclotetramethylene tetranitramine (HMX) derivatives modified with amido groups and the bond dissociation energy of the weakest N-NO2 bond. The bond dissociation energy decreases with the number of amido groups. Isodesmic reactions were used to calculate standard molar enthalpies of formation of the derivatives; these values increase with the number of amido groups but not according to additivity rules. Entropy and heat capacity were also investigated. NBO analysis was applied to study the bond orders and the second perturbation energy of the N-NO2 bonds; these parameters decrease regularly with the number of amido groups. Taking a single amido derivative as an example to analyze the vibration frequencies, it is shown that all the strongest vibrations are related with the N-NO2 bonds.
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