论文标题
运动方程MLCCSD和CCSD-IN-HF振荡器强度及其在核心激发中的应用
Equation-of-motion MLCCSD and CCSD-in-HF oscillator strengths and their application to core excitations
论文作者
论文摘要
我们提出了多级CCSD（MLCCSD）模型的运动方程振荡器强度的实现，其中CCS用作较低级别方法（CCS/CCSD）。在此模型中，群集操作员的双重激发仅限于活动的轨道空间，而单个激发不受限制。计算出的腺苷，三磷酸腺苷（ATP）和ATP水系统的氮K边缘光谱用于证明模型的性能。投影的原子轨道（PAO）用于将虚拟空间划分为主动和不活跃的轨道集。 Hartree-fock密度的Cholesky分解用于划分占据轨道。这种cholesky-pao的分区便宜，将其缩放为$ \ Mathcal {o}（n^3）$，并且适合计算本地性格的核心激励。通过将群集操作员的单个激发限制为活动空间以及双激发，可以获得CCSD-IN-HF模型。为腺苷和ATP系统的核心激发光谱提供了两个模型--- MLCCSD和CCSD-IN-HF的比较。
We present an implementation of equation-of-motion oscillator strengths for the multilevel CCSD (MLCCSD) model where CCS is used as the lower level method (CCS/CCSD). In this model, the double excitations of the cluster operator are restricted to an active orbital space, whereas the single excitations are unrestricted. Calculated nitrogen K-edge spectra of adenosine, adenosine triphosphate (ATP), and an ATP-water system are used to demonstrate the performance of the model. Projected atomic orbitals (PAOs) are used to partition the virtual space into active and inactive orbital sets. Cholesky decomposition of the Hartree-Fock density is used to partition the occupied orbitals. This Cholesky-PAO partitioning is cheap, scaling as $\mathcal{O}(N^3)$, and is suitable for the calculation of core excitations which are localized in character. By restricting the single excitations of the cluster operator to the active space, as well as the double excitations, the CCSD-in-HF model is obtained. A comparison of the two models---MLCCSD and CCSD-in-HF---is presented for the core excitation spectra of the adenosine and ATP systems.
