Thiele Mark, Kümmel Stephan
Physikalisches Institut, Universität Bayreuth, D-95440, Bayreuth, Germany.
Phys Chem Chem Phys. 2009 Jun 14;11(22):4631-9. doi: 10.1039/b902567g. Epub 2009 Apr 22.
Photoabsorption spectra for 2-electron singlet systems are obtained from the real-time propagation of the time-dependent Kohn-Sham equations in the adiabatically exact approximation. The latter is provided by the exact ground state exchange-correlation potential corresponding to the instantaneous density. The results are compared to exact data obtained from the solution of the interacting Schrödinger equation. We find that the adiabatically exact approximation provides very good results for transitions of genuinely single excitation character but yields incorrect results if double excitations contribute substantially. However, the extent of the error can vary: some double excitations are just shifted in energy whereas others are missed completely. These situations are analyzed with the help of transition densities.
通过在绝热精确近似下对含时Kohn-Sham方程进行实时传播，得到了双电子单重态系统的光吸收光谱。后者由对应于瞬时密度的精确基态交换关联势给出。将结果与从相互作用薛定谔方程解中获得的精确数据进行比较。我们发现，绝热精确近似对于具有真正单激发特征的跃迁能给出非常好的结果，但如果双激发贡献显著，则会产生错误结果。然而，误差程度可能不同：一些双激发只是能量发生了偏移，而另一些则完全被遗漏。借助跃迁密度对这些情况进行了分析。
