Chen Jun, Xu Jiani, Xiao Tingting, Ma Peng, Ma Congming
College of Safety Science and Engineering, Nanjing Tech University, Nanjing, 211816, China.
J Mol Model. 2024 Jul 29;30(8):290. doi: 10.1007/s00894-024-06093-x.
To explore the influence of the external electric field (EEF) on ε-CL-20. The molecular structure, frontier molecular orbitals (FMOs), global reactivity parameters (GRP), surface electrostatic potential, nitro charge, and UV-Vis spectra of ε-CL-20 under EEF were studied using density functional theory (DFT). The calculation results show that the electric field applied along N16-N24 has a significant effect on the structure of ε-CL-20. With an increase in the positive EEF, the bond length of the initiating bond decreases, and the bond order and bond dissociation energy increase, which increases the thermal stability of ε-CL-20 to a certain extent. In addition, with an increase in the positive EEF intensity, the LUMO migrates from both sides of the positive electric field to one side of the nitro group, and the HOMO migrates from the skeleton to the nitro group. It is worth noting that in the negative EEF, when the electric field strength changed from 0 to 0.016 a.u., the negative charge of the total nitro group gradually decreased. When the electric field strength becomes 0.02 a.u., the negative charge of the total nitro group suddenly increases, and ε-CL-20 is significantly polarized. When the electric field strength is sufficiently strong, the occupied and unoccupied orbitals of the ε-CL-20 molecule change, resulting in a change in the energy level difference between the occupied and unoccupied orbitals, which further excites the corresponding excited state, resulting in a new UV-Vis absorption peak.
Based on the density functional theory (DFT), the structural optimization and energy calculation were carried out by using B3LYP/6-311 + G(d, p) and B3LYP/def2-TZVPP methods, respectively. After optimization convergence, vibration analysis was performed without imaginary frequencies to obtain stable configurations. Then the molecular structure, frontier molecular orbitals (FMOs), global reactivity parameters (GRP), surface electrostatic potential, nitro charge, and UV-Vis spectra were analyzed.
探究外部电场（EEF）对ε-六硝基六氮杂异伍兹烷（ε-CL-20）的影响。采用密度泛函理论（DFT）研究了EEF作用下ε-CL-20的分子结构、前沿分子轨道（FMO）、全局反应性参数（GRP）、表面静电势、硝基电荷和紫外可见光谱。计算结果表明，沿N16-N24施加的电场对ε-CL-20的结构有显著影响。随着正EEF的增加，引发键的键长减小，键级和键解离能增加，这在一定程度上提高了ε-CL-20的热稳定性。此外，随着正EEF强度的增加，最低未占分子轨道（LUMO）从正电场两侧迁移至硝基一侧，最高已占分子轨道（HOMO）从骨架迁移至硝基。值得注意的是，在负EEF中，当电场强度从0变为0.016原子单位时，总硝基的负电荷逐渐减少。当电场强度变为0.02原子单位时，总硝基的负电荷突然增加，且ε-CL-20发生显著极化。当电场强度足够强时，ε-CL-20分子的占据轨道和未占据轨道发生变化，导致占据轨道和未占据轨道之间的能级差改变，进而激发相应的激发态，产生新的紫外可见吸收峰。
基于密度泛函理论（DFT），分别采用B3LYP/6-311+G(d, p)和B3LYP/def2-TZVPP方法进行结构优化和能量计算。优化收敛后，进行无虚频的振动分析以获得稳定构型。然后分析分子结构、前沿分子轨道（FMO）、全局反应性参数（GRP）、表面静电势、硝基电荷和紫外可见光谱。
