The Li-centered “ferric wheel” molecules with six oxo-bridged iron atoms form molecular crystals. We probed their electronic structure by X-ray photoelectron (XPS) and soft X-ray emission spectroscopy (XES), having calculated in parallel the electronic structure of a single “ferric wheel” molecule from first-principles by tools of the density-functional theory, using, specifically, the Siesta m...

We show that multiple suboptimal splice sites underlie the thermal-sensitive splicing of the period (per) 3'-terminal intron (dmpi8) from D. melanogaster, enabling this species to prolong its midday "siesta," a mechanism that likely diminishes the deleterious effects of heat during the longer summer days in temperate climates. In D. yakuba and D. santomea, which have a more ancestral distributi...

We propose a computational method that simplifies drastically the inclusion of spin-orbit interaction in density functional theory when implemented over localised atomic orbital basis sets. Our method is based on a well-known procedure for obtaining pseudopotentials from atomic relativistic ab initio calculations and on an on-site approximation for the spin-orbit matrix elements. We have implem...

The past two decades have witnessed substantial progress in methodology and knowledge in sleep research all over the world. The paper at hand will present some recent local contributions to this field. The first is a European project (SIESTA) focusing on the creation of an automatic sleep classification system and a normative database, including polysomnographic (PSG) and psychometric measures,...

Under the application of a strong electric field, atoms from a metal surface can rupture their bonds and escape, leading to ‘field-evaporation’. We present a firstprinciples description of this phenomenon, taking as an example the evaporation of Al adatoms from an Al(111) surface. The ‘charged-plane’ method [A.Y. Lozovoi and A. Alavi, Phys Rev B 68, 246416 (2003)], has been implemented in the c...

We compare the results of ab initio calculations of the interaction of Si tips with the surfaces of CaCO3, MgO, and CaF2. The calculations were performed using the density functional theory and the SIESTA code. We used a conventional Si tip model with a dangling bond at the apex. The results demonstrate a considerable electron density redistribution between the tip and surface, which depends on...

Decentralized Trust Management, originally introduced by the PolicyMaker and SDSI prototypes, and currently promoted at least by the KeyNote2, SPKI, and TeSSA development efforts, provides a means of distributed authorization that seems to be especially suitable for distributed object systems and agent based systems. In this paper we introduce the SIESTA project, which studies how to integrate ...

The structure and stability of periodic solid phosphorus carbide phases P4C3 8n (n 0–4) are studied at zero and high pressure using periodic density functional theory as implemented in the codes SIESTA and CASTEP. For each composition a range of structures is examined, including both defective diamond-like and graphitic-like structures. At zero pressure the lowest energy structure for P4C3 (n 0...

We investigate the electronic structure of gap and band tail states in amorphous silicon. Starting with two 216-atom models of amorphous silicon with defect concentration close to the experiments, we systematically study the dependence of electron localization on basis set, density functional, and spin polarization using the first-principles density-functional code SIESTA. We briefly compare th...