Time-dependent density-functional theory (TDDFT) describes the quantum dynamics of
interacting electronic many-body systems formally exactly and in a practical and efficient …

We describe the formalism, as well as numerical and implementation issues behind
PARSEC–the pseudopotential algorithm for real‐space electronic structure calculations. Its …

We present a broadly applicable, physically motivated, first-principles approach to
determining the fundamental gap of finite systems from single-electron orbital energies. The …

We present x-ray absorption and emission experiments and ab initio calculations showing
that the size of carbon diamond must be reduced to at least 2 nm, in order to observe an …

We employ density functional and quantum Monte Carlo calculations to show that significant
changes occur in the gap of fully hydrogenated nanoclusters when the surface contains …

Time-dependent density-functional theory (TDDFT) extends the basic ideas of ground-state
density-functional theory (DFT) to the treatment of excitations and of more general time …

The difference between oxide and hydrogen passivation of small Si nanocrystals is explored
by all-electron, hybrid functional DFT calculations with unrestricted geometry optimization …

Doped nanocrystalline silicon (nc-Si: H) thin films offer improved carrier transport
characteristics and reduced parasitic absorption compared to amorphous silicon (a-Si: H) …

Quantum Monte Carlo (QMC) calculations of the optical gaps of silicon quantum dots
ranging in size from 0 to 1.5 nm are presented. These QMC results are used to examine the …

We report first-principles calculations for optical absorption spectra of hydrogenated silicon
clusters in the presence of oxygen on the surface. Our computational technique is based on …