Conical intersections and double excitations in time-dependent density functional theory

摘要: There is a clear need for computationally inexpensive electronic structure theory methods which can model excited state potential energy surfaces. Time-dependent density functional (TDDFT) has emerged as one of the most promising contenders in this context. Many previous tests have concentrated on vertical excitation energies, be compared to experimental absorption maxima. Here, we focus attention more global aspects resulting surfaces, especially conical intersections play key role photochemical mechanisms. We introduce new method minimal intersection (MECI) searches does not require knowledge non-adiabatic coupling vector. Using method, compute MECI geometries with multi-state complete active space perturbation (MS-CASPT2) and TDDFT. show that TDDFT linear response adiabatic approximations predict energetics quite accurately, but there are number qualitative deficiencies addressed before used routinely problems.