A dynamic-correlation doubles correction to CASSCF linear response excitation energies

该项目的目标是对CASSCF线性响应（MCRPA）激发能引入双倍(D)校正。这种激励-能量校正以微扰的方式引入了动态相关，将显著提高MCRPA的精度。结合MCRPA(D)方法，可以精确计算中型开壳过渡金属配合物的局部激发和电荷转移激发的核和价激发能。用现有的方法，目前还不能以令人满意的方式进行这些计算。此外，我将对可能发生在开壳轨道附近简并TMC中的自旋翻转跃迁进行(D)校正。为了实现更大的活动空间(D)计算，将追求对所谓的库普曼矩阵进行有效的重新表述。

The goal of the project is the introduction of a doubles (D) correction to CASSCF linear response (MCRPA) excitation energies. This excitation-energy correction introduces dynamical correlation in a perturbative manner and will significantly improve the accuracy of MCRPA. With the combined MCRPA(D) method, the calculation of accurate core and valence excitation energies of medium-sized open-shell transition metal complexes will be possible for both local and charge-transfer excitations. With existing methods, these calculations are currently not yet possible in a satisfactory fashion. Moreover, I will work on a formulation and implementation of a (D) correction for spin-flip transitions that occur likely in open-shell orbital-near degenerate TMC. To enable larger-active space (D) calculations, an efficient reformulation of so-called Koopmans matrices will be pursued.