Fukui Institute for Fundamental Chemistry, Kyoto University, Takano-Nishihiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103, Japan.
J Chem Phys. 2017 Apr 7;146(13):134114. doi: 10.1063/1.4979672.
A theory for dynamics of molecular photoionization from nonadiabatic electron wavepackets driven by intense pulse lasers is proposed. Time evolution of photoelectron distribution is evaluated in terms of out-going electron flux (current of the probability density of electrons) that has kinetic energy high enough to recede from the molecular system. The relevant electron flux is in turn evaluated with the complex-valued electronic wavefunctions that are time evolved in nonadiabatic electron wavepacket dynamics in laser fields. To uniquely rebuild such wavefunctions with its electronic population being lost by ionization, we adopt the complex-valued natural orbitals emerging from the electron density as building blocks of the total wavefunction. The method has been implemented into a quantum chemistry code, which is based on configuration state mixing for polyatomic molecules. Some of the practical aspects needed for its application will be presented. As a first illustrative example, we show the results of hydrogen molecule and its isotope substitutes (HD and DD), which are photoionized by a two-cycle pulse laser. Photon emission spectrum associated with above threshold ionization is also shown. Another example is taken from photoionization dynamics from an excited state of a water molecule. Qualitatively significant effects of nonadiabatic interaction on the photoelectron spectrum are demonstrated.
提出了一种由强脉冲激光驱动的非绝热电子波包分子光致电离动力学理论。根据具有足够高动能以从分子体系中退离的出射电子流（电子密度概率流的电流）来评估光电子分布的时间演化。反过来，通过在激光场中非绝热电子波包动力学中时间演化的复值电子波函数来评估相关的电子流。为了通过电离失去其电子密度的电子波函数的唯一性重建，我们采用从电子密度中出现的复值自然轨道作为总波函数的构建块。该方法已被实现到量子化学代码中，该代码基于多原子分子的组态态混合。将介绍其应用所需的一些实际方面。作为第一个说明性示例，我们展示了由双周期脉冲激光光致电离的氢分子及其同位素取代物（HD 和 DD）的结果。还显示了与阈上电离相关的光子发射光谱。另一个例子取自水分子激发态的光致电离动力学。展示了非绝热相互作用对光电子谱的定性重要影响。
