We present various types of reduced models including five vibrational modes and three electronic states for the pyrazine molecule in order to investigate the lifetime of electronic coherence in a rigid and neutral system. Using ultrafast optical pumping in the ground state (1 1 A g ), we prepare a coherent superposition of two bright excited states, 1 1 B 2u and 1 1 B 1u , and reveal the effect of the nuclear motion on the preservation of the electronic coherence induced by the laser pulse. More specifically, two aspects are considered: the anharmonicity of the potential energy surfaces and the dependence of the transition dipole moments (TDMs) with respect to the nuclear coordinates. To this end, we define an ‘ideal model’ by making three approximations: (i) only the five totally symmetric modes move, (ii) which correspond to uncoupled harmonic oscillators, and (iii) the TDMs from the ground electronic state to the two brig...

中文翻译：

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中性和刚性多原子分子在电子波包中保持相干性

为了研究吡嗪分子的五个振动模式和三个电子状态，我们提出了各种简化模型，以研究刚性和中性系统中电子相干的寿命。使用基态（1 1 A g）中的超快光泵浦，我们准备了两个明亮的激发态1 1 B 2u和1 1 B 1u的相干叠加，并揭示了核运动对电子的保存的影响激光脉冲引起的相干性。更具体地说，考虑了两个方面：势能表面的非谐性以及跃迁偶极矩（TDM）相对于核坐标的依赖性。为此，我们通过以下三种近似来定义“理想模型”：（i）只有五个完全对称的模态运动，