外场下丙烯酸甲酯的激发特性研究

Excited states structure for methyl acrylate under external electric field

采用密度泛函B3LYP方法在6-311++G**基组上优化了不同外电场作用下丙烯酸甲酯分子的基态几何结构、电偶极矩和分子的总能量,并且分析了分子的HOMO-3到LUMO+3轨道的能量变化,然后利用杂化CIS-DFT方法(CIS-B3LYP)在相同基组下探讨了无电场时丙烯酸甲酯分子前9个激发态的激发能、波长和振子强度和外电场对丙烯酸甲酯分子激发态的影响规律.结果表明,分子的几何构型与外电场大小有着较强的依赖关系.随着外电场的增大,分子总能量先增大后减小,电偶极矩μ先减小后增大,激发能随电场增加快速减小,表明在外电场作用下,丙烯酸甲酯分子易于激发和离解,激发态波长随电场的增大而不断增大,且其电子跃迁光谱涵盖紫外区到红外区.

The ground state parameters, the dipole moment, the charge distribution and the energies of MOs of methyl acrylate under different intense electric fields are optimized using the density functional theory （DFT）B3LYP based on the 6-311＋ ＋G＊ ＊ basis set level. The excitation energies, the wavelengths, the oscillator strengths from ground state to the first nine different excited states are calculated employing the revised hybrid CIS-DFT method （CIS-B3LYP） without external electric field, and the excited states under different electric fields are also investigated. The results show that the molecular geometry is strongly dependent on electric field strength, and the energy proves to increase before decreasing but the dipole moment behaves in a contrary manner. The excitation energies of the first nine excited states of methyl acrylate decrease with the increase of the applied electric field, indicating that the molecule is easy to excite and dissociate in the electric field .The wavelength is also increase with the increase of electric field, and its electronic transition spectrum covers from the ultraviolet to infrared.