Daniel Sánchez-Portal

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Dynamical processes are commonly investigated using laser pump-probe experiments, with a pump pulse exciting the system of interest and a second probe pulse tracking its temporal evolution as a function of the delay between the pulses. Because the time resolution attainable in such experiments depends on the temporal definition of the laser pulses, pulse(More)
Hematite (a-Fe 2 O 3) has demonstrated value as an important material component in several advanced technological applications, including heterogeneous catalysis, [1] photoelec-trochemistry, [2,3] dyes and stains, [4] magnetic data storage, [5] and room-temperature magnetic semiconductors. [6,7] The structure and properties of hematite also have critical(More)
We present a combined experimental and theoretical study of the electronic properties of close-spaced dangling-bond (DB) pairs in a hydrogen-passivated Si(001):H p-doped surface. Two types of DB pairs are considered, called "cross" and "line" structures. Our scanning tunneling spectroscopy (STS) data show that, although the spectra taken over different DBs(More)
The electronic structure of an infinite poly-guanine-poly-cytosine DNA molecule in its dry A-helix structure is studied by means of density-functional calculations. An extensive study of 30 nucleic base pairs is performed to validate the method. The electronic energy bands of DNA close to the Fermi level are then analyzed in order to clarify the electron(More)
In the context of linear scaling methods for electronic structure and molecular dynamics calculations, SIESTA was developed as a fully first-principles method able to deal with systems with an unprecedented number of atoms, with a modest computational workload. The method has allowed us to study a large variety of problems involving nanoscale materials,(More)
Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon(More)
: Recent advances in attosecond spectroscopy techniques have fueled the interest in the theoretical description of electronic processes taking place in the subfemtosecond time scale. Here we study the coupled dynamic screening of a localized hole and a photoelectron emitted from a metal cluster using a semi-classical model. Electron density dynamics in the(More)
Gold deposited on silicon surfaces at the monolayer regime results in a variety of reconstructions. The most interesting ones are the (quasi-) one dimensional phases, featuring monatomic wires of gold. They promise exotic physical phenomena, such as the Luttinger liquid [1]. These wires can be grown on the flat Si(111) surface which yields three possible(More)
We present a systematic Density Functional Theory (DFT) study of geometries and energies of the nucleic acid DNA bases (guanine, adenine, cytosine and thymine) and 30 different DNA base-pairs. We use a recently developed linear-scaling DFT scheme, which is specially suited for systems with large numbers of atoms. As a first step towards the study of large(More)
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