CO oxidation on ${\mathrm{T}\mathrm{i}\mathrm{O}}_2$ supported Au has been studied using density functional theory calculations. Important catalytic roles of the oxide have been identified: (i) CO oxidation occurs at the interface between Au and the oxide with a very small barrier; and (ii) ${\mathrm{O}}_2$ adsorption at the interface is the key step in the reaction. The physical origin of the oxide promotion effect has been further investigated: The oxide enhances electron transfer from the Au to the antibonding states of ${\mathrm{O}}_2$, giving rise to (i) strong ionic bonding between the adsorbed ${\mathrm{O}}_2$, Au, and the Ti cation; and (ii) a significant activation of ${\mathrm{O}}_2$ towards CO oxidation.

We show that first-principles electronic structure calculations of silicon wires with diameters up to ∼1.5 nm support the idea that quantum confinement and surface effects are responsible for the luminescence in porous silicon. Instead of the indirect gap of crystalline bulk silicon, the band structure of these wires exhibits a direct gap at k=0. The imaginary part of the dielectric function, polarized in the direction of the wire, shows a peak in the visible range. The dependence of this feature on wire size is analyzed and correlated to experimental luminescence spectra.

Electronic structure problems are studied in condensed matter physics and theoretical chemistry to provide important insights into the properties of matter. This 2006 graduate textbook describes the main theoretical approaches and computational techniques, from the simplest approximations to the most sophisticated methods. It starts with a detailed description of the various theoretical approaches to calculating the electronic structure of solids and molecules, including density-functional theory and chemical methods based on Hartree-Fock theory. The basic approximations are thoroughly discussed, and an in-depth overview of recent advances and alternative approaches in DFT is given. The second part discusses the different practical methods used to solve the electronic structure problem computationally, for both DFT and Hartree-Fock approaches. Adopting a unique and open approach, this textbook is aimed at graduate students in physics and chemistry, and is intended to improve communication between these communities. It also serves as a reference for researchers entering the field.

We present a practical scheme for performing ab initio supercell calculations of charged slabs at constant electron chemical potential μ, rather than at constant number of electrons $N_e.$ To this end, we define the chemical potential relative to a plane (or “reference electrode”) at a finite distance from the slab (the distance should reflect the particular geometry of the situation being modeled). To avoid a net charge in the supercell, and thus make possible a standard supercell calculation, we restore the electroneutrality of the periodically repeated unit by means of a compensating charge, whose contribution to the total energy and potential is subtracted afterwards. The “constant μ” mode enables one to perform supercell calculation on slabs, where the slab is kept at a fixed potential relative to the reference electrode. We expect this to be useful in modeling many experimental situations, especially in electro-chemistry.