外电场中OH分子的激发与势能函数

Study on molecular properties and potential energy function of OH under external electric field

摘要:

本文采用MPW1PW91/Aug-cc-pvtz方法和基组, 优化了OH自由基分子在不同电场强度下的几何结构, 并对该分子的能量, 振动频率, 偶极矩, 红外光谱与电子激发, 势能函数等进行了计算. 计算结果显示：能量随着外电场的增加出现减小趋势, 频率则是先增大后减小, 偶极矩一直增加；电场从-0.02 a.u.数值增大致-0.05 a.u.与0.00 a.u.增大到0.05 a.u., 红外光谱发生红移, 在0.00 a.u.到 -0.02 a.u.红外谱发生蓝移；无电场时激发波长均处于紫外区域, 激发态中未见有能量简并现象出现；有电场时, 振子强度受电场影响很大, 一些禁阻跃迁的谱线被激发出来, 且电场对UV-Vis吸收光谱影响甚大；进行单点势能函数Morse势函数拟合, 拟合得到的势参数与实验值、文献值基本符合. 电场导致OH分子的势能深度逐渐减小, 降低了OH解离能.

Abstract:

Using MPW1PW91/Aug-cc- PVTZ method and basis set, the physical properties of OH molecule under different electric fields were obtained, including the bond length, energy, vibration frequency, infrared spectrum, dipole moment, potential energy function and so on. Results show that with the increase of electric field, the energy decreases continuously, the frequency increases first and then decreases, and the dipole moment increases monotonously. The infrared spectrum has a blue shift. When the electric field is absent, the stimulated wavelength is located in the ultra-violate region, there is no energetic degeneration, the strength of oscillation is also influenced strongly, and some forbidden spectra are also stimulated up. Therefore, the electric field has a great influence on UV-VIs absorbing spectra. The Morse potential function is simulated, and the parameters are consistent with the values among experiments and literature. The electric field also declines the depth of potential of OH molecular, which makes the dissociating energy of OH molecular lower.