氟利昂F13在外电场中的分子特性研究

Investigation on molecular properties of freon 13 in external electric field

利用密度泛函理论（Density functional theory，DFT）在B3LYP／6-311＋＋G（d，声）水平上研究了外电场（-15．43～15．43V／nm）对氟利昂F13（三氟氯甲烷，CRCl）分子物理和光谱特性的影响．计算结果表明，在C～Cl键连线z方向上，外电场从-15．43V／nm逐渐增加到15．43V／nm时，分子体系能量先增大后降低，偶极矩表现为先减小后增大，能隙ElG先增加后减小，C-Cl键键长逐渐增大，C-F键键长逐渐减小．外电场对CRCl分子红外振动光谱的频率和强度也有影响．进一步研究发现在外电场作用（O到15．43V／nm）逐渐增强下，CRCl分子的势能曲线束缚形态逐渐被解开，解离的势垒逐渐减小．在强度为15.43V／nm的电场作用下，CF3Cl分子将会发生C-C1键断裂而降解，该结果为对氟利昂进行外电场降解提供重要的参考依据．

Density functional theory （DFT） at B3LYP/6-311q-q-G（d,p） level is used for the investi- gation of physical properties and spectra of Freon 13 （CF3C1） in external electric field. Calculated re- sults show that, with increasing the external field from --15.43 to 15.43 V/nm along the molecular axis z gradually, and total energy first increases and then decreases, while dipole moment decreases at the beginning and then increases. Energy gaps increases and then decreases. C--C1 bond length in- creases while C--F bond length decreases. At the same time, the trend of vibrational frequency and intensity of molecular IR spectra in external electric field are also explored. Further studies show that with increasing gradually the external electric field from 0 to 15.43 V/nm, the dissociation PES along C--C1 bond becomes unbond with disappearing of the dissociation barrier. In the external electric field of 15.43 V/nm, CF3C1 occurs degradation with breaking of C--C1 bond. Such results provide an im- portant reference for the degradation of freon in the external electric field.