基于非正交定域分子轨道计算非线性光学性质的程序开发和应用

Based on the demand of high accuracy and high efficiency of quantum chemistry program for nonlinear optical properties of materials, this project is to develop a new method and a program to calculate NLO (hyper)polarizabilities for large systems. Linear scaling methods based on orthogonal localized orbitals often observe the long-range non-localized tails due to its orthogonality requirement. Quantum chemistry methods based on non-orthogonal localized molecular orbitals (NOLMO) are more realized recent years. This proposal is going to use NOLMOs to develop a new quantum chemistry method and a program suite to calculate the nonlinear optical properties for large systems. In this work, we first construct NOLMO vacant orbitals from the NOLMO occupied orbitals. Then we derive the time-dependent coupled perturbed Hartree-Fcok equations and the program. The purpose of this project is to work out a linear scaling quantum chemistry program suite and its applications for NLO properties of large systems.

面对高精度高效率的量子化学计算程序在研究非线性光学材料方面的需求，拟发展一套基于非正交定域分子轨道的、计算非线性光学极化率和超极化率的量子化学方法和程序。基于正交定域分子轨道的线性标度方法时常面临由于正交限制而产生的长程定域尾巴的难题。由于非正交定域分子轨道具有轨道定域性好的优势，成为近年来研究的热点，也是计算化学领域今后的发展方向之一。本项目在获得非正交定域占据分子轨道的基础上，构建非正交定域的空轨道，推导出基于非正交定域分子轨道的含时耦合Hartree-Fock方程（NOLMO-TDHF），发展出一套高效率线性标度的计算非线性光学性质的理论方法，编制出相应的计算程序包，并应用于大体系的非线性光学性质的研究。该程序方法的实现可以达到线性标度计算非线性光学材料的极化率和超极化率的目标。

本项目“基于非正交定域分子轨道计算非线性光学性质的程序开发和应用”（项目批准号：21673085，执行日期2017.1.1-2020.12.31）发展了一套基于非正交定域分子轨道的计算非线性光学极化率和超极化率的量子化学方法和程序。在能量最优化方法的基础上获得了非正交定域占据分子轨道，进而采用投影算符的方法构建了非正交定域的空轨道；推导出基于非正交定域分子轨道的含时耦合Hartree-Fock方程（NOLMO-TDHF）以及含时耦合DFT方程（NOLMO-TDDFT），发展出一套高效率线性标度的计算非线性光学性质的理论方法，并编制出相应的计算程序包，可以应用于大体系的非线性光学性质的研究。