OH自由基分子的外电场特性研究

Properties of Ground State for OH Radicals in Different External Electric Fields

采用MPW1PW91/Aug-cc-pvqz方法及基组探索电场对OH自由基基态分子的总能量、键长、偶极矩、谐振频率、红外谱强度、电荷布居、HOMO和LUMO能级的影响.计算结果表明:MPW1PW91方法优化得到的核间距为Re=0.096 973nm,与实验值Re=0.096 96nm符合得非常好,只有0.001 3%的误差;振动频率为3 739.403cm^(-1),也与NIST数据库实验值3 737.76cm^(-1)一致;键长和红外谱强度随电场的增加先减小后增大;HOMO能和谐振频率分子总能量随电场的增加先增大后减小;偶极矩随电场增加线性地增加,LUMO能级随电场增加平缓地增加;E_g随外电场的增大先增大后减小.电场中OH自由基分子被激发至空轨道形成空穴时,该分子对电场强度具有选择性.

The density functional theoretical method with Aug-cc-pvqz basis sets（MPW1 PW91/Aug-ccpvqz）was adopted to study the total energy,bond length,dipole moment,harmonic frequency,infrared intensity,atomic charge distribution,and HOMO（the highest occupied molecular orbital energy level）and LUMO（the lowest unoccupied molecular orbital energy level）of the OH radical ground state molecules in electric fields with different intensities.The results showed that the equilibrium structure was highly consistent with experiment data,the error being 0.001 3% only.The harmonic frequency（f=3 739.403 cm^-1 ）also well agreed with the experiment data of the NIST database（f=3 737.76 cm^-1）.With the increase of the external electric field,bond length and infrared intensity decreased first,and then increased;in contrast,HOMO energy level and harmonic frequency were observed to increase first and decrease afterwards.The electric dipole moments were noticed to increase linearly,and LUMO energy level was found to increase slowly.The energy gap（Eg）increased first,and then decreased.The external electric field intensity was selected by the OH radical molecules,when it was excited.