Quantum-Chemical Study on Magnetic Molecular Properties andChemical Reactions in Excited States Based on the RelativisticSAC-CI Theory

本项目的主要目的是对高阶相对论GUHF-CCSD-CI方法在电子激发态下的化学反应和化学现象进行新的理论和计算发展，例如考虑自旋轨道相互作用和系间交叉的光化学反应和精细势能面。在GUHF-CCSD-CI方法中，GUHF轨道用作参考，CCSD用于电子基态。我们编制了GUHF-CCSD-CI方法的计算机程序，并将其应用于单重态和三重态激发态的计算，并与非相对论CCSD SO-CASPT 2方法进行了比较。GUHF-CCSD-CI比其他方法更准确。SO-CASPT 2在轻元素中准确，但在重元素中不准确。此外，我们还对含重元素的化合物进行了相对论量子化学计算。

The main purpose of this project is to make a new theoretical and computational development of the higher-order relativistic GUHF-CCSD-CI method for chemical reactions and chemical phenomena in the electronic excited states, for example, photochemical reactions and fine potential energy surface considering the spin-orbit interaction and the intersystem crossing. In the GUHF-CCSD-CI method, the GUHF orbitals are used as reference and the CCSD is used for the electronic ground state. We finished the computer code of the GUHF-CCSD-CI method, and we applied this code to calculations of the singlet and triplet excited states and checked the accuracy in comparison with the non-relativistic CCSD, SO-CASPT2. The GUHF-CCSD-CI is meaningfully more accurate than the other methods. The SO-CASPT2 is accurate in light elements but not in heavy elements. Further, we carried out some relativistic quantum-chemical calculations for compounds containing heavy-elements.