甲烷在外场作用下的光激发特性研究

采用密度泛函B3LYP和组态相互作用方法在6-311++G^**水平上计算了甲烷从基 态到前六个激发态的跃迁波长，振子强度，自发辐射系数A_n0和吸收系数B _0n（ n=1—6）.同时研究了外电场对甲烷分子的激发态的影响规律.结果表明，随外电场强度增大 ，系统总能量变化较小，同时最高占据轨道HOMO与最低空轨道LUMO的能隙gaps变小，费米能 级Fermi levels略有下降.甲烷基态（X～^lＡ_l）在外场作用下，易 于向高激发态产生跃迁.关键词：4')" href="#">CH₄激发态外电场

Study on the effect of external electric field excitation on methane

The present paper is devoted to the calculation of transition wavelengths, os cillator strengths f, Einstein A_n0 and B_0n coefficients of methane from ground state Ｘ～^lＡ_l to the first six di fferent excited states by employing density functional theory and single substitute con figuration interaction (CIS) approach with basis sets 6-311++G^**. At the same time, the excited states of methane under an external electric field are i nvestigated. It is shown that the total energy of the system has little change d, and simultaneously the HOMO-LUMO gaps become small and the Fermi levels dec lines slightly as the external electric field intensity become strong. The trans ition between ground state Ｘ～^lＡ_l and the high-excited state of methane is easy bring about.