Acocella Angela, Jones Garth A, Zerbetto Francesco
Dipartimento di Chimica G. Ciamician, Università di Bologna, V. F. Selmi 2, 40126, Bologna, Italy.
J Phys Chem A. 2006 Apr 20;110(15):5164-72. doi: 10.1021/jp060195i.
This paper describes an electron dynamics method where the time dependence of an external oscillating electric field is the perturbing part of the Hamiltonian. Application of the electric field induces charge movement inside the molecule and electronic transitions between the molecular orbitals. The test system is the neutral LiH molecule. The method is applied to wave functions calculated using the B3LYP (hybrid) density functional, with the STO-3G and the 6-31+G basis sets. The molecule undergoes full population inversion between the HOMO and the LUMO when the electric field is in resonance with the HOMO-LUMO energy gap. The magnitude of the electric field directly affects the rate at which electronic transitions occur and the rate at which charges move between lithium and hydrogen atoms. The method is used to model both monochromatic and bichromatic multiphoton effects in LiH. Monochromatic one-, two- and three-photon transitions occur between the HOMO, LUMO and two other virtual orbitals. There is evidence of both [1+2] direct and [1+1+1] stepwise multiphoton transitions. Bichromatically, two "laser" pulses are applied at different frequencies. Electronic transitions can be fine-tuned to occur via pre-specified pathways of virtual molecular orbitals.
本文描述了一种电子动力学方法，其中外部振荡电场的时间依赖性是哈密顿量的微扰部分。施加电场会引起分子内部的电荷移动以及分子轨道之间的电子跃迁。测试系统为中性LiH分子。该方法应用于使用B3LYP（杂化）密度泛函、STO - 3G基组和6 - 31 + G基组计算得到的波函数。当电场与HOMO - LUMO能隙共振时，分子在HOMO和LUMO之间发生完全布居反转。电场强度直接影响电子跃迁发生的速率以及电荷在锂原子和氢原子之间移动的速率。该方法用于模拟LiH中的单色和双色多光子效应。在HOMO、LUMO和另外两个虚拟轨道之间发生单色单光子、双光子和三光子跃迁。存在[1 + 2]直接和[1 + 1 + 1]逐步多光子跃迁的证据。在双色情况下，以不同频率施加两个“激光”脉冲。电子跃迁可以通过虚拟分子轨道的预先指定路径进行微调。
