We study proton diffusion in amorphous SiO2 from the atomic scale to the long-range percolative regime. Ab initio molecular dynamics suggest that the dominant atomic process consists in cross-ring interoxygen hopping assisted by network vibrations. A stati ...
We discuss various decomposition schemes for analysing the dielectric constants of Zr silicates in terms of local properties. Such schemes serve the purpose of predicting the dielectric constants of amorphous alloys, when their system size precludes the po ...
We develop a theory for investigating atomic-scale dielectric permittivity profiles across interfaces between insulators. A local susceptibility chi(x;omega) is introduced to describe variations of the dielectric response over length scales of the order of ...
We present a spin delocalization effect in radical Si-containing systems, featuring a heteroatom of high electronegativity (such as N, O, or Cl) bonded to the unsaturated Si atom. We find that the higher the electronegativity of the heteroatom, the more th ...
We carried out an ab initio molecular dynamics simulation of liquid hydrogen. chloride (l-HCl) at a temperature of 313 K. Comparison with inelastic neutron scattering data shows that the simulation achieves an overall good description of the structural cor ...
We describe a scheme for calculating the infrared and Raman spectra of large model structures from first principles. Our scheme is based on the application of a finite electric field in density functional calculations with periodic boundary conditions. Cou ...
Using a density-functional approach, we investigate the reactivity of supported metal nanoclusters. We focus on the sequential adsorption of N-2 molecules on a Fe nanocluster supported by an MgO substrate. For an increasing number of N atoms preadsorbed on ...
We investigated the oxidation reaction of the O-2 molecule at the Si(100)-SiO2 interface by using a constrained ab initio molecular dynamics approach. To represent the Si(100)-SiO2 interface, we adopted several model interfaces whose structural properties ...
We determine the fraction f of B atoms belonging to boroxol rings in vitreous boron oxide through a first-principles analysis. After generating a model structure of vitreous B2O3 by first-principles molecular dynamics, we address a large set of properties, ...
We analyze the principal vibrational spectra of vitreous GeO2 and derive therefrom structural properties referring to length scales beyond the basic tetrahedral unit. We generate a model structure that yields a neutron structure factor in accord with exper ...
We carried out an ab initio investigation of the charged states of hydrogen in amorphous SiO2 using a previously generated model structure. We found a large variety of equilibrium configurations as a result of the disordered atomic structure in our model s ...
We model the fundamental kinetic processes occurring during silicon oxidation at the atomic scale. We first focus on the diffusion of the, neutral O-2 molecule through the oxide layer. By combining ab initio and classical simulations, we derive a statistic ...
Using density functional theory, we investigate the structural, vibrational, and dielectric properties of titanium oxides and silicates, which have attracted considerable attention in the framework of the quest for alternative high-K materials. For the oxi ...
Through the sequential use of classical molecular dynamics and first-principles relaxation methods, we generate an abrupt model interface for the 4H(0001)SiC-SiO2 interface showing regular structural parameters without any coordination defect. The bond den ...
We review the structural and hyperfine properties of Si dangling bond defects occurring in amorphous SiO2 and at various Si-SiO2 interfaces. These defects have in common a singly occupied orbital on a, trivalent Si Centre. We first briefly summarize the mo ...
The method for treating finite electric fields within periodic boundary conditions is used to formally define a density functional depending on the electric field. An exchange and correlation energy functional depending on the electric field is introduced ...
We introduce a general scheme for calculating from first principles both the transverse-optical and longitudinal-optical infrared absorption spectra at surfaces or interfaces. A spatial decomposition of the spectra gives the evolution of the infrared activ ...
We discuss the structural, electronic and dielectric properties of a model structure of the Si(100)-SiO2 interface that accounts for the amorphous nature of the oxide. After showing that the structural properties of this model are consistent with a variety ...
