We study the nonadiabatic dynamics of an electronic wave packet on two coupled potential energy surfaces. We focus on the difference between two configurations, the presence of a conical intersection (CI) and an avoided crossing (AC). We project the time-dependent dynamics onto the tuning and the coupling modes. For weak intersurface coupling, no significant difference appears. However, significant differences in the deactivation of the wave packet arise for increasing intersurface coupling. Most striking is a strong destructive interference of the two pathways of the wave packet which differ by a factor of $\pi$ when moving around the CI. This yields to a vanishing of the wave packet in the CI configuration, which does not exist with an avoided crossing. By this, it is straightforward to identify the geometric phase in the wave packet dynamics and to use it to distinguish a CI from an AC configuration.

我们研究了两个耦合的势能面上电子波包的非绝热动力学。我们着眼于两种配置之间的差异，即锥形交叉点（CI）和避免交叉点（AC）的存在。我们将与时间有关的动力学投影到调整和耦合模式上。对于弱的表面间耦合，没有显着差异。然而，为了增强表面间的耦合，波包的去激活出现了明显的差异。最令人震惊的是，波包的两个路径之间的相消系数相差很深，造成了很大的破坏性干扰。$\pi$在CI周围移动时。这导致在CI配置中波包消失，这在避免交叉的情况下是不存在的。这样，可以直接确定波包动力学中的几何相位，并使用它来将CI与AC配置区分开。