论文标题
DFT/MRCI的扰动近似：DFT/MRCI（2）
A perturbative approximation to DFT/MRCI: DFT/MRCI(2)
论文作者
论文摘要
我们对组合密度功能理论和多方面构型相互作用（DFT/MRCI）方法引入了扰动近似。该方法称为DFT/MRCI（2），是由准脱氧扰动理论和DFT/MRCI Hamiltonian矩阵的Epstein-nesbet分区的应用而产生的。这导致用小小的有效的哈密顿量替换了大型DFT/MRCI Hamiltonian的对角线化，并在计算成本方面可以节省数量级。此外，发现DFT/MRCI（2）近似具有极好的精度，可以为一组广泛的有机分子测试集的根平方平方平方偏离dft/MRCI值小于0.03 eV的兴奋能。
We introduce a perturbative approximation to the combined density functional theory and multireference configuration interaction (DFT/MRCI) method. The method, termed DFT/MRCI(2), results from the application of quasi-degenerate perturbation theory and the Epstein-Nesbet partitioning of the DFT/MRCI Hamiltonian matrix. This results in the replacement of the diagonalization of the large DFT/MRCI Hamiltonian with that of a small effective Hamiltonian, and affords orders of magnitude savings in terms of computational cost. Moreover, the DFT/MRCI(2) approximation is found to be of excellent accuracy, furnishing excitation energies with a root mean squared deviation from the DFT/MRCI values of less than 0.03 eV for an extensive test set of organic molecules.
