Electrical response of molecular systems: the power of self-interaction corrected Kohn-Sham theory

The accurate prediction of electronic response properties of extended molecular systems has been a challenge for conventional, explicit density functionals. We demonstrate that a self-interaction correction implemented rigorously within Kohn-Sham theory via the Optimized Effective Potential (OEP) yields polarizabilities close to the ones from highly accurate wavefunction-based calculations and exceeding the quality of exact-exchange-OEP. The orbital structure obtained with the OEP-SIC functional and approximations to it are discussed.Comment: accepted for publication in Physical Review Letter

Size effects in the interface level alignment of dye-sensitized TiO 2 clusters

The efficiency of dye-sensitized solar cells (DSCs) depends critically on the electronic structure of the interfaces in the active region. We employ recently developed dispersion-inclusive density functional theory (DFT) and GW methods to study the electronic structure of TiO2 clusters sensitized with catechol molecules. We show that the energy level alignment at the dye-TiO2 interface is the result of an intricate interplay of quantum size effects and dynamic screening effects and that it may be manipulated by nanostructuring and functionalizing the TiO2. We demonstrate that the energy difference between the catechol LUMO and the TiO2 LUMO, which is associated with the injection loss in DSCs, may be reduced significantly by reducing the dimensions of nanostructured TiO2 and by functionalizing the TiO2 with wide-gap moieties, which contribute additional screening but do not interact strongly with the frontier orbitals of the TiO2 and the dye. Precise control of the electronic structure may be achieved via "interface engineering" in functional nanostructures. © 2014 American Chemical Society

Orbital Density Reconstruction for Molecules

The experimental imaging of electronic orbitals has allowed one to gain a fascinating picture of quantum effects. We here show that the energetically high-lying orbitals that are accessible to experimental visualization in general differ, depending on which approach is used to calculate the orbitals. Therefore, orbital imaging faces the fundamental question of which orbitals are the ones that are visualized. Combining angular-resolved photoemission experiments with first-principles calculations, we show that the orbitals from self-interaction-free Kohn-Sham density functional theory are the ones best suited for the orbital-based interpretation of photoemission