外电场下氮化铝分子结构和光谱研究

Molecular Structure and Spectrum of Aluminium Nitride Molecule under the External Electric Field

以6-311+G(2DF)为基函数,采用密度泛函B3P86的方法研究了外电场作用下氮化铝(AlN)基态分子的几何结构、HOMO能级、LUMO能级、能隙及谐振频率.结果表明,外电场的大小和方向对AlN分子基态的这些性质有明显影响.在所加的电场范围内,随着外电场的增大分子键长减小,谐振频率增大,总能量升高,在F=0.02a.u.时能量达到最大,为-297.4217a.u.,此后继续增大电场强度,系统总能量则开始降低;EH和EL随着电场的增加均逐渐增大,在F=0.01a.u.时,EH和EL均取得最大值,分别为-0.2776和-0.0828a.u.,随着电场的继续增大,能级EH和EL均逐渐减小,而能隙在外电场增大的过程中始终处于减小趋势.

A density functional method （B3P86） with 6-311＋G（2DF） basis has been used to study the equilibrium geometry, HOMO energy level, LUMO energy level, energy gap and harmonic frequency of aluminium nitride （AlN） ground state molecule under different external electric field ranging from -0.03 to 0.03 a.u. The results show that the magnitude and direction of the external electric field have important effects on these characteristics of the AlN molecule. The bond length and energy gap were found to decrease, but the harmonic frequency, HOMO energy level and LUMO energy level were found to increase with increasing the external field. The maximum HOMO energy level and LUMO energy level were -0.2776 and -0.0828 a.u. at F=0.01 a.u, respectively. Further increasing the electric field would make the HOMO energy level and LUMO energy level decreased. As the electric field increased to 0.02 a.u., the total molecule energy reached the maximum -297.4217 a.u. Further increasing the electric field resulted in a decrease of the total energy.