摘要
本文用MCSCF/CI方法对NH_3,CH_5^+和CH_6^(2+)的基态和激发态进行了理论计算,结果表明:NH_3的A^1A_2″态和a^3A_2″态是Rydberg性质的激发态,并且都是解离性的激发态,解离过程是一个从Rydberg态向分子价态转变的过程;CH_5^+的A^1A′态和a^3A′态是Rydberg性和分子价态的混合;CH_6^(2+)的A^1A_1态和a^3A_1态是完全的分子价态。计算还指出,NH_3的X^1A_1′态是束缚态,CH_5^+和CH_6^(2+)的基态及各激发态中均存在三中心双电子作用。文中还给出了各个激发态的垂直跃迁能量和单重—三重分裂能,并从成键特征解释了激发态的性质及其对单重—三重分裂能的影响。
The ground states and the excited states of NH_3, CH_5^+ and CH_6^+ are investigated by MCSCF / CI calculations. It is found that the A^IA_2~H states and that a^3A_2~H states of NH_3 are dissociative Rydberg states, and that the dissociation proceses are regarded as the Rydbergization processes. The calculations indicated that the A^IA'state and the a^3A'state of CH_5^+ are the stutes mixed the Rydberg states with the molecular valence states, and that the A^IA_I state and the a^3A_1 states of CH_6^+ are completely molecular valence states. The calcula- tions also found that the X^IA_2~' state of NH_3 is a bound sstate, and that the three-center- two-clectron interaction exists in the ground states and the excited states of CH_5^+ and CH_6^+. The vertical transition energies of the excited states and the singlet-triplet splitting energies are give and explained from the chemical bonds molecular orbitals.
