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溴甲烷分子(CH_3Br)是一种十分重要的工业原料,但它也是一种消耗臭氧层的物质,是大气主要污染物之一.因此,研究其降解的条件具有十分重要的意义.为了研究外电场作用下溴甲烷的光谱和解离特性,本文采用了密度泛函理论(density functional theory,DFT),在6-311++G(d,p)基组水平上使用B3LYP方法研究了不同的外电场(0-0.05a.u.)对于溴甲烷分子的键长、能隙以及解离势能面的影响.计算结果表明:外加电场的方向和大小对于分子结构和解离势能面均有显著的影响.随着负向外电场(Br-C键方向)从0增加到0.05a.u.,C-Br键的键长先减小后增大,C-H键的键长逐渐增加,分子能隙EG逐渐减小,C-Br键的str振动频率逐渐增加而IR振动频率逐渐减小.通过进一步计算发现:随着正向外电场(C-Br键方向)从0增加到0.03a.u.,溴甲烷分子的势能曲线有所降低,解离势垒逐渐减小.因此,可以通过改变外电场来控制CH3Br分子的降解.
Methyl bromide (CH 3 Br) is a very important industrial raw material, but it is also an ozone-depleting substance and one of the major pollutants in the atmosphere. Therefore, it is of great significance to study the conditions of its degradation.In order to study the effect of external electric field In this work, the density functional theory (DFT) was used to study the spectra and dissociation properties of methyl bromide. The B3LYP method was used to study the effects of different external electric fields on the 6-311 ++ G (d, p) -0.05au) on the bond length, energy gap and dissociation potential energy of the methyl bromide molecule.The calculated results show that the direction and size of the applied electric field have a significant effect on the molecular structure and the dissociation potential energy surface.With the negative outward electric field (Br-C bond direction) increased from 0 to 0.05 Au, the bond length of C-Br bond first decreased and then increased, the bond length of CH bond increased gradually, the molecular energy gap EG gradually decreased, The frequency of vibration increases gradually and the frequency of IR decreases gradually.Further calculations show that the potential energy curve of methyl bromide molecules decreases with increasing the forward external electric field (C-Br bond direction) from 0 to 0.03au. The dissociation barrier Therefore, it is possible to control CH by changing the external electric field 3Br molecule degradation.