Mechanism and molecular design of nonlinear optical properties originating in the flexibility of complex electronic systems

阐明了开壳系统产生非线性光学现象的机理。本研究首先阐明了磁相互作用与三阶NLO性质之间的密切联系，然后通过调整双自由基特征和自旋态构建了新的NLO性质控制准则。提出了几种实际开壳分子的计算方法，并设计了一类新的开壳NLO分子。我们还开发了一种基于从头算MO方法的量子主方程方法，并成功地计算了动态NLO响应。

We clarified the mechanism of generating nonlinear optical (NLO) phenomena of open-shell systems. The present study first elucidated a close connection between the magnetic interaction and third-order NLO properties, and then constructed novel control guidelines for NLO properties by tuning the diradical character and spin states. Several calculation methods for real open-shell molecules were proposed, and a new class of open-shell NLO molecules was designed. We also developed a quantum master equation approach based on the ab initio MO method, and succeeded in calculating dynamic NLO responses.