Persona: Fernández Sánchez, Eva María
Cargando...
Dirección de correo electrónico
ORCID
0000-0003-2085-0478
Fecha de nacimiento
Proyectos de investigación
Unidades organizativas
Puesto de trabajo
Apellidos
Fernández Sánchez
Nombre de pila
Eva María
Nombre
6 resultados
Resultados de la búsqueda
Mostrando 1 - 6 de 6
Publicación Ergotropy and entanglement in critical spin chains(American Physical Society, 2023-02-08) Mula, Begoña; Fernández, Julio J.; Santalla, Silvia N.; Alvarellos Bermejo, José Enrique; García Aldea, David; Rodríguez Laguna, Javier; Fernández Sánchez, Eva MaríaA subsystem of an entangled ground state (GS) is in a mixed state. Thus, if we isolate this subsystem from its surroundings, we may be able to extract work applying unitary transformations, up to a maximal amount which is called ergotropy. Once this work has been extracted, the subsystem will still contain some bound energy above its local GS, which can provide valuable information about the entanglement structure. We show that the bound energy for half a free fermionic chain decays as the square of the entanglement entropy divided by the chain length, thus approaching zero for large system sizes, and we conjecture that this relation holds for all one-dimensional critical states.Publicación Nanowire reconstruction under external magnetic fields(AIP, 2020-12-23) Santalla, Silvia N.; Rodríguez Laguna, Javier; Fernández Sánchez, Evamaría; Alvarellos Bermejo, José Enrique; Rodríguez Laguna, Javier; Fernández Sánchez, Eva MaríaWe consider the different structures that a magnetic nanowire adsorbed on a surface may adopt under the influence of external magnetic or electric fields. First, we propose a theoretical framework based on an Ising-like extension of the 1D Frenkel–Kontorova model, which is analyzed in detail using the transfer matrix formalism, determining a rich phase diagram displaying structural reconstructions at finite fields and an antiferromagnetic–paramagnetic phase transition of second order. Our conclusions are validated using ab initio calculations with density functional theory, paving the way for the search of actual materials where this complex phenomenon can be observed in the laboratory.Publicación Colaboraciones en Física: Nanoagregados para el almacenamiento de hidrógeno(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2018-01-01) Fernández Sánchez, Eva MaríaPublicación Sequential adsorption of multiple CO molecules on Au10-and Au9Zn-triangular clusters: The crucial role of a single atomic impurity(Royal Society of Chemistry, 2025-02-05) Fernández Sánchez, Eva María; Balbás, Luis C.In this paper, we find, using DFT calculations, that the patterns of sequential adsorption sites of up to six CO molecules on the planar Au10− and Au9Zn− clusters differ radically. Thus, CO prefers bridge (top) adsorption sites forming Au10(CO)n− compounds with n = 1–3 (n = 4–5), but top (bridge) sites occur for Au9Zn(CO)n− compounds when n = 1–4 (n = 5–6). These facts are distinguishable in the CO stretching spectra of both types of compounds. Severe distortions and broken Au–Au bonds appear in the morphology of pure compounds after CO adsorption, but only small distortions are seen in the doped compounds. Using the nudged elastic band (NEB) method, we find the reaction paths of CO adsorption for pure n = 3 and doped n = 5 compounds. The estimated reaction barrier of the pure compound is much higher than that of the doped one. We also find important differences in the electronic properties of these compounds as functions of the size n: adsorption energy, bond lengths, angles, Bader atomic charges, and HOMO–LUMO gaps. We argue that all these differences are due to a larger charge reorganization in the doped than in the pure gold compounds, because of the Zn atom's lower electronegativity than that of gold and carbon. Comparison with previous results for multiple adsorption of NO molecules sheds light on the characteristics of Au–CO and Au–NO bonds.Publicación Adsorption of multiple NO molecules on Au10− and Au9Zn− planar clusters. A comparative DFT study(Royal Society of Chemistry, 2023-06-01) Fernández Sánchez, Eva María; Balbás, Luis C.The doping of atomic clusters with transition-metal atoms modifies to a lesser or greater extent the catalytic properties of the pure forms. Here we study by means of density functional theory (DFT) the adsorption of up to six NO molecules on Au10− and Au9Zn− clusters, both with well-tested D3h planar geometry, to learn how precise modifications of the atomic and electronic environment, namely one atom and a valence electron, affect the bonding of multiple NO molecules to anionic gold clusters. First, we confirm that these clusters have D3h symmetry as determined by L. S. Wang and coworkers using photoelectron spectroscopy experiments [Kulichenko et al., J. Phys. Chem. A, 2021, 125, 4606]. Second, we verify that Au10(NO)n− with n ≤ 6 does not form adsorbed (NO)2 dimers, as realized by the experiments of Ma and coworkers [Ma et al., Phys. Chem. Chem. Phys., 2020, 22, 25227] using a mini flow-tube reactor at 150 K. Third, we discover that the ground state of the doped Au9Zn(NO)6− compound forms a (NO)2cis-dimer bridging two non-corner Au atoms of the Au9Zn(NO)4− compound. The discussion of adsorption energies, spin multiplicities, bond lengths, charge trends, vibrational strength frequencies of adsorbed NO's, and projected density of states (PDOS), brings additional testable differences between Au10(NO)n− and Au9Zn(NO)n− compounds (n ≤ 6).Publicación Interactions of nitric oxide molecules with pure and oxidized silver clusters /AgnO± (n=11–13): A computational study(American Institute of Physics, 2022-08-18) Fernández Sánchez, Eva MaríaIn this work, we have studied, within density functional theory, the interaction of NO with pure and oxidized silver clusters, both anionic and cationic, composed from 11 to 13 Ag atoms. In that size interval, shell closing effects are not expected, and structural and electronic odd–even effects will determine the strength of interaction. First, we obtained that species Ag±n and AgnO± with odd number of electrons (n = 12) adsorb NO with higher energy than their neighbors (n = 11 and 13). This result is in agreement with the facts observed in recent mass spectroscopy measurements, which were performed, however, at finite temperature. The adsorption energy is about twice for oxidized clusters compared to pure ones and higher for anions than for cations. Second, the adsorption of another NO molecule on AgnNO± forms Agn(NO)±2 , with the dimer (NO)2 in cis configuration, and binding the two N atoms with two neighbor Ag atoms. The n = 12 species show the higher adsorption energy again. Third, in the absence of reaction barriers, all complexes Agn(NO)±2 dissociate spontaneously into AgnO± and N2O, except the n = 12 anion. The maximum high barrier along the dissociation path of Ag13(NO)−2 is about 0.7 eV. Further analysis of projected density of states for Ag11−13(NO)±x (x = 0, 1, 2) molecules shows that bonding between NO and Ag clusters mainly occurs in the energy range between −3.0 and 3.0 eV. The overlap between 4d of Ag and 2p of N and O is larger for Ag12(NO)±2 than for neighbor sizes. For n = 12, the d bands are close to the (NO)2 2π orbital, leading to extra back-donation charge from the 4d of Ag to the closer 2π orbital of (NO)2.