外电场作用下甲基乙烯基硅酮分子结构和电子光谱  

Molecular Structure and Electronic Spectrum for Methyl Vinyl Siloxane under the External Electric Field

作　　者：徐国亮[1] 肖小红[1] 刘玉芳[1] 孙金锋[1] 朱正和[2] 

机构地区：[1]河南师范大学物理与信息工程学院,河南新乡453007 [2]四川大学原子与分子物理研究所,成都610065

出　　处：《物理化学学报》2007年第5期746-750,共5页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(10376022);河南师范大学博士科研启动基金(051003)资助项目

摘　　要：采用密度泛函B3P86方法在6-311++G(d,p)基组水平上优化得到了沿分子轴方向不同外电场(0-0.04a.u.)作用下,甲基乙烯基硅酮分子的基态电子状态、几何结构、电偶极矩和分子总能量.在优化构型下利用杂化CIS-DFT方法(CIS-B3P86)研究了同样外电场条件下对甲基乙烯基硅酮的激发能和振子强度的影响.计算结果表明,分子几何构型与电场大小呈现强烈的依赖关系,分子偶极矩μ随电场的增加先减小后急剧增大.电场为零时,分子总能量为-483.5532137a.u.,随着电场增加,能量升高,在F=0.02a.u.时达到最大值-483.5393952a.u.,此后,继续增大电场系统总能量则开始降低.激发能随电场增加急剧减小,表明在电场作用下,分子易于激发和离解.The ground states of methyl vinyl siloxane under different intense electric fields ranging from O to 0.04 a.u. were optimized using density functional theory DFT/B3P86 at 6-311＋＋G（d,p） level. The excitation energies and oscillator strengths under the same intense appfied electric fields were calculated employing the revised hybrid CIS-DFT method. The result showed that the electronic state, molecular geometry, total energy, dipole moment, and excitation energy were strongly dependent on the applied electric field. As the electric field changed from 0 to 0.03 a, u., the bond length of Si-O decreased because of the charge transfer induced by the applied electric field. Further increase of the electric field resulted in an increase of the bond length. The dipole moment of the ground state increased sharply with the applied field strength. As the electric field increased to 0.02 a.u., the total energy of the molecule reached the maximum -483.5393952 a.u.. Further increase of the electric field strengths resulted in a decrease of the total energy. The excitation energies of the first five excited states of methyl vinyl siloxane decreased as the increase of the applied electric field, indicating that the molecule was easy to be excited under electric field and hence could be easily dissociated.

关 键 词：甲基乙烯基硅酮 电场 激发态 杂化CIS—DFT 

分 类 号：O621.13[理学—有机化学]