Nitrogen doping-induced changes in the electronic properties, defect formation, and surface structure of TiO2 rutile(110) and anatase(101) single crystals were investigated. No band gap narrowing is observed, but N doping induces localized N 2p states within the band gap just above the valence band. N is present in a N(III) valence state, which facilitates the formation of oxygen vacancies and ...

Weshow that repulsive local Coulomb interaction alone can drive valence-skipping charge disproportionation in the degenerate d-band, resulting in effective negative-U . This effect is shown to originate from anisotropic orbitalmultipole scattering, and it occurs only for d1, d4, d6, and d9 fillings (and their immediate surroundings). Explicit boundaries for valence-skipping are derived, and the...

The band structure of strained Si ~4–10 ML! on ~001! GaAs, band lineups of the strained Si/~001!GaAs heterojunction, and confined energy levels of the Si3N4 /Si/GaAs quantum well have been calculated via a pseudopotential method. It has been found that in this technically important Si3N4 /Si/~001!GaAs structure, strained Si has a very narrow band gap ~0.34 eV! at the D' point in the Brillouin z...

PbSe is a pseudo-II-VI material distinguished from ordinary II-VI's (e.g., CdSe, ZnSe) by having both its valence band maximum (VBM) and its conduction band minimum (CBM) located at the fourfold-degenerate L-point in the Brillouin zone. It turns out that this feature dramatically affects the properties of the nanosystem. We have calculated the electronic and optical properties of PbSe quantum d...

In recent years, the spin dynamics and spin–orbit interaction in GaAs-based two-dimensional hole systems (2DHS) have created a lot of attention. This is due to the complex structure of the valence band, with its p-like character, which leads to strong spin–orbit coupling. In this paper, we review our recent studies on hole spin dynamics and valence-band spin excitations in GaAs-based, p-modulat...

The present study was designed to test differential hemispheric activation induced by emotional stimuli in the gamma band range (30-90 Hz). Subjects viewed slides with differing emotional content (from the International Affective Picture System). A significant valence by hemisphere interaction emerged in the gamma band from 30-50 Hz. Other bands, including alpha and beta, did not show such an i...