Numerical Liouville approach: A calculation method for nonlinear optical susceptibilities of N-state systems.
Numerical Liouville approach: A calculation method for nonlinear optical susceptibilities of N-state systems.
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数值刘维尔方法：N 态系统非线性光学磁化率的计算方法。
DOI：
10.1103/physreva.50.2989
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Yamaguchi
中科院分区：
文献类型：
--
作者：
Nakano;Yamaguchi
利用Liouville方程数值精确解的傅里叶变换，发展了一种计算N态量子系统与强多色场相互作用的n阶非线性光学系数χ g（n）（ω）的方法.这是一种非微扰方法，可以提供真实的和虚的非线性光谱，适用于任意激光强度，频率和弛豫。作为该方法的应用，我们研究了两种类型的三，四，和十六状态模型，模拟电子激发态的反式辛四烯从一个完整的配置相互作用计算使用的巴黎-帕尔-波普哈密顿。基于微扰方法导出的虚激发过程，我们还分析了这些模型在非共振区的光谱特征，并指出第一离子态B u1之上的第二个Ag 1激发态是描述定性χ g（3）（ω）值的关键，而不是第一离子态B u1之下的第一个Ag 1激发态.此外，对于只包含非共振过程的模型和包含双光子共振过程的模型，阐明了χ g（3）（ω）的真实的部分随各激发态跃迁性质（跃迁能量和跃迁矩）的变化特征.
We develop an alternative calculation method for the nth-order nonlinear optical susceptibilities χ g (n)(ω), for N-state quantum systems interacting with intense polychromatic fields, by means of the Fourier transformation of numerically exact solutions of the Liouville equation. This is a nonperturbative method that can provide both real and imaginary nonlinear optical spectra, valid for arbitrary laser intensities, frequencies, and relaxation. As applications of the method, we examine two types of three-, four-, and sixteen-state models that mimic the electronic excited states of trans octatetraene obtained from a full configuration-interaction calculation using the Pariser-Parr-Pople Hamiltonian. We also analyze the characteristics of the spectra in the off-resonance region for these models based on virtual excitation processes derived from the perturbative approach, and show that the second A g 1 excited state above the first ionic B u 1 state is essential for describing a qualitative χ g (3)(ω) value rather than the first A g 1 excited state below the first B u 1 state. Furthermore, the characteristics of variations in the real part of χ g (3)(ω) with the transition properties (transition energies and moments) of each excited state are elucidated both for a model only including the off-resonance process and a model including a two-photon resonance process.