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(NLO)现象的机制。本研究首先阐明了磁相互作用与三阶非线性光学性质之间的密切联系，然后通过调节双基性质和自旋态，构建了新的非线性光学性质控制指南。提出了几种实际开壳分子的计算方法，设计了一类新的开壳NLO分子。我们还发展了一种基于从头算MO方法的量子主方程方法，并成功地计算了动态非线性光学响应。

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.