Golubev Nikolay V, Begušić Tomislav, Vaníček Jiří
Laboratory of Theoretical Physical Chemistry, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2020 Aug 21;125(8):083001. doi: 10.1103/PhysRevLett.125.083001.
Irradiation of a molecular system by an intense laser field can trigger dynamics of both electronic and nuclear subsystems. The lighter electrons usually move on much faster, attosecond timescale but the slow nuclear rearrangement damps ultrafast electronic oscillations, leading to the decoherence of the electronic dynamics within a few femtoseconds. We show that a simple, single-trajectory semiclassical scheme can evaluate the electronic coherence time in polyatomic molecules accurately by demonstrating an excellent agreement with full-dimensional quantum calculations. In contrast to numerical quantum methods, the semiclassical one reveals the physical mechanism of decoherence beyond the general blame on nuclear motion. In the propiolic acid, the rate of decoherence and the large deviation from the static frequency of electronic oscillations are quantitatively described with just two semiclassical parameters-the phase space distance and signed area between the trajectories moving on two electronic surfaces. Because it evaluates the electronic structure on the fly, the semiclassical technique avoids the "curse of dimensionality" and should be useful for preselecting molecules for experimental studies.
用强激光场照射分子系统会引发电子和原子核子系统的动力学过程。较轻的电子通常移动速度快得多，在阿秒时间尺度上，但缓慢的原子核重排会阻尼超快的电子振荡，导致电子动力学在几飞秒内退相干。我们表明，一种简单的单轨迹半经典方案可以通过与全维量子计算显示出极好的一致性，准确评估多原子分子中的电子相干时间。与数值量子方法不同，半经典方法揭示了退相干的物理机制，而不仅仅是将其归咎于原子核运动。在丙炔酸中，仅用两个半经典参数——相空间距离和在两个电子表面上移动的轨迹之间的带符号面积，就可以定量描述退相干速率以及与电子振荡静态频率的大偏差。由于半经典技术可以即时评估电子结构，因此避免了“维度诅咒”，应该有助于为实验研究预选分子。
