We implement a flexible Z-matrix approach in the Density Functional Theory (DFT) periodic boundary conditions code, SIESTA. This allows a mixture of Z-matrix and Cartesian coordinates to be used for geometry specification and optimisation. In addition, geometry constraints in the form of fixed coordinates and fixed linear relationships between coordinates can be specified. A Z-matrix approach i...

The electronic structure of Cu hexafluoroacetylacetonate, crystallized with a stable nitronyl nitrox-ide radical [Ovcharenko et al., Russ. Chem. Bull. 53, 2406 (2004)], is calculated from first principles within the density functional theory using the SIESTA method, in two magnetic configurations reflecting parallel or antiparallel setting of S = 1/2 spins of Cu(II) ions to those of organic rad...

En el presente estudió teórico comparativo se utiliza código SIESTA, utilizando como base la Teoría del Funcional de Densidad (DFT) llevando a cabo modelado y optimización las superaleaciones Ni: AlNi3 ScNi3 en su fase cristalina cúbica centrada caras (FCC) para entender propiedades estructurales, electrónicas ópticas. Empleando pseudopotencial base: Aproximación Gradiente Generalizado (GGA) po...

The siesta habit is associated with a 37% reduction in coronary mortality, possibly because of reduced cardiovascular stress associated with daytime sleep. Whether the most important behavior is the daytime nap itself, a supine posture, or the expectancy of a nap is unknown. We present the first detailed description on healthy individuals of the acute changes in cardiovascular function during d...

In this paper we study electron dynamics and transport in models of amorphous silicon and amorphous silicon hydride. By integrating the time-dependent Kohn–Sham equation, we compute the time evolution of electron states near the gap, and study the spatial and spectral diffusion of these states due to lattice motion. We perform these calculations with a view to developing ab initio hopping trans...