Lehrstuhl für Theoretische Physik, Universität Paderborn, 33098 Paderborn, Germany.
J Comput Chem. 2013 May 5;34(12):1035-45. doi: 10.1002/jcc.23230. Epub 2013 Jan 8.
Based on the equilibrium geometries of Cu2(dbdmed)2O2 and Cu2(en)2O2 obtained within density-functional theory, we investigate their molecular electronic structure and optical response. Thereby results from occupation-constrained as well as time-dependent DFT (ΔSCF and TDDFT) are compared with Green's function-based approaches within many-body perturbation theory such as the GW approximation (GWA) to the quasiparticle energies and the Bethe-Salpeter equation (BSE) approach to the optical absorption. Concerning the ground-state energies and geometries, no clear trend with respect to the amount of exact exchange in the DFT calculations is found, and a strong dependence on the basis sets is to be noted. They affect the energy difference between bis-μ-oxo and μ-η(2):η(2)-peroxo complexes by as much as 0.8 eV (18 kcal/mol). Even stronger, up to 5 eV is the influence of the exchange-correlation functional on the gap values obtained from the Kohn-Sham eigenvalues. Not only the value itself but also the trends observed upon the bis-μ-oxo to μ-η(2):η(2)-peroxo transition are affected. In contrast, excitation energies obtained from ΔSCF and TDDFT are comparatively robust with respect to the details of the calculations. Noteworthy, in particular, is the near quantitative agreement between TDDFT and GWA+BSE for the optical spectra of Cu2(en)2O2.
基于密度泛函理论得到的Cu2(dbdmed)2O2和Cu2(en)2O2的平衡几何结构，我们研究了它们的分子电子结构和光学响应。因此，比较了占据约束和含时密度泛函理论（ΔSCF 和 TDDFT）与基于多体微扰理论的方法的结果，如准粒子能量的 GW 近似（GWA）和光学吸收的玻色-爱因斯坦方程（BSE）方法。关于基态能量和几何形状，在 DFT 计算中，没有发现与精确交换量明显相关的趋势，并且强烈依赖于基组。它们影响了双μ-氧和μ-η(2):η(2)-过氧络合物之间的能量差多达 0.8 eV（18 kcal/mol）。更强的是，交换相关函数对从 Kohn-Sham 本征值获得的间隙值的影响高达 5 eV。不仅是值本身，而且在双μ-氧到μ-η(2):η(2)-过氧转变过程中观察到的趋势也受到影响。相比之下，来自 ΔSCF 和 TDDFT 的激发能对于计算的细节相对稳健。值得注意的是，TDDFT 与 GWA+BSE 对Cu2(en)2O2的光学光谱的接近定量一致性。
