外场下SnO分子结构和特性研究

对Ｓｎ原子采用ＳＤＢ-ｃｃ-ｐＶＴＺ基组，Ｏ原子采用 ６-３１１＋＋Ｇ基组，利用密度泛函中的 Ｂ３Ｐ８６方法对 ＳｎＯ分子的基态结构进行了优化计算，并研究了外场对 ＳｎＯ基态分子的键长、总能、电荷布居分布、能级分布、电偶极矩、谐振频率和红外谱强度的影响。并利用杂化密度泛函理论（ＣＩＳ ＤＦＴ）方法研究了外电场对 ＳｎＯ分子由基态到前 ６个单重激发态跃迁规律的影响。结果表明，在所加电场范围内，随着正向电场 Ｆ的逐渐增大，基态分子的键长 Ｒｅ先减小后增大，在 Ｆ＝００４ａ．ｕ．时取得最小值 ０１７９６ｎｍ；总能先增大后减小，其在 Ｆ＝００３ａ．ｕ．时取得最大值 －２１４４８３９６ｅＶ；电偶极矩则先减小后增大，在 Ｆ＝００３ａ．ｕ．时取得最小值 ０２１２４Ｄｅｂｙｅ；ＳｎＯ基态分子的最高已占据轨道（ＨＯＭＯ）能量 ＥＨ和谐振频率逐渐增大；红外光谱强度、分子的最低未占空轨道（ＬＵＭＯ）能量ＥＬ和能隙 Ｅｇ则逐渐减小。外电场的大小与方向对跃迁电偶极矩、跃迁波长、激发能和振子强度均有很大影响。

SnO molecular structure and properties under external electric field

The structure of SnO ground state molecule is optimized by employing density functional theory （B3P86） method with SDB-cc-pVTZ basis sets for Sn atom and 6-311 ＋＋ G for O atom. The effects of electric filed on the bond length, total energy, mulliken atomic charges, the Highest Occupied Molecular Orbital（HOMO） energy level, the Lowest Unoccupied Molecular Orbital （LUMO） energy level, energy gap, electric dipole moment, harmonic fre- quency and infrared intensity of SnO ground state molecule are studied. The excited properties of SnO molecule under different electric fields are also investigated by using configuration interaction singles density functional theory （ CIS- B3P86） method. The results show that the bond length and electric dipole moment are found to firstly decrease, then increasing with increasing of positive direction electric fields, the minimums are 0. 179 6 nm at F = 0. 04 a.u. and 0. 212 4 Debye at F =0. 03 a. u. , respectively. The total energy is proved to firstly increase, then decreasing with in- creasing of positive direction electric fields, the maximum is - 2 144. 839 6 eV at F = 0. 03 a. u.. The En and harmonic frequency are found to increase with increasing of positive direction electric fields, but the EL, Eg and infrared intensity are decreasing. The magnitude and direction of the external electric field have important effects on excitation energies, oscillator strengths and the wavelength.