David López-Durán

David López-Durán
University of Cordoba (Spain) | UCO · Department of Physics

D.Phil.

About

36
Publications
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602
Citations

Publications

Publications (36)
Article
First-principles electronic structure calculations are now accessible to a very large community of users across many disciplines, thanks to many successful software packages, some of which are described in this special issue. The traditional coding paradigm for such packages is monolithic, i.e., regardless of how modular its internal structure may...
Article
Full-text available
The variation of the HOMO-LUMO band gap is explored for varying packing arrangements of the 4mod BT-4TIC donor-acceptor molecule pair, by means of a high-throughput ab-initio random structure search of packing possibilities. 350 arrangements of the dimer have been relaxed from initial random dispositions, using non-local density-functional theory....
Article
The variation of the HOMO-LUMO band gap is explored for varying packing arrangements of the 4mod BT-4TIC donor-acceptor molecule pair, by means of a high-throughput ab-initio random structure search of packing possibilities. 350 arrangements of the dimer have been relaxed from initial random dispositions, using non-local density-functional theory....
Preprint
Full-text available
First-principles electronic structure calculations are very widely used thanks to the many successful software packages available. Their traditional coding paradigm is monolithic, i.e., regardless of how modular its internal structure may be, the code is built independently from others, from the compiler up, with the exception of linear-algebra and...
Article
Water dissociation is crucial in many catalytic reactions on oxide-supported transition-metal catalysts. Supported by experimental and density-functional theory results, the effect of the support on OH bond cleavage activity is elucidated for nickel/ceria systems. Ambient-pressure O 1s photoemission spectra at low Ni loadings on CeO2(111) reveal a...
Article
We present in this work a potential energy surface of the (X4Σ)KRb-K complex for which high level ab initio calculations have been carried out at the RCCSD(T) level of theory, using ECP10MDF/ECP28MDF effective core potentials and basis sets for K/Rb, respectively, with the dimer at its lowest triplet state and fixed to the equilibrium distance. The...
Article
The energetics and structures of HeNCa clusters have been studied by means of path integral Monte Carlo calculations. Sizes ranging between N = 10 and 40 helium atoms were considered at T = 1, 1.5, and 2 K. Radial and angular distributions have been analyzed in detail to investigate the geometry of the bound systems. The comparison of the results o...
Article
Full-text available
Doped HeN Rb2 (3Σ u +) systems, with N = 20 and 40, have been studied by means of a path integral Monte Carlo method at two different temperatures T = 1 K and 2 K. The impurity, Rb2, is assumed as a rigid rotor and results are compared with a previous analysis in which no rotational or translational degrees of freedom were taken into account. Quant...
Article
Diffusion and path integral Monte Carlo methods are currently, and successfully, used to describe structures and binding energies of helium clusters doped with some impurity. For diatomic dopants, by considering the He atoms as "electrons" and the dopant as "nuclei" within a Hartree/Hartree-Fock framework, our group has developed a complementary to...
Article
Bound states of 40Ca-nHe2, n=3,4, triatomic complexes are investigated. The potential-energy surface, represented as the addition of atomic-pair interactions, is that recently used to study these systems by Gou and Li, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.85.012510 85, 012510 (2012). The results obtained from three different methods, in fair...
Article
We discuss the computational results on the energetics and features of the bound states of one and two He atoms attached to a Ca atom, which have been presented by Gou and Li in a recently published paper in Phys. Rev. A 85, 012510 (2012). We show that, given their choice for the interaction potential-energy surface, the energy they found for the t...
Article
We present in this paper binding energies and structures of non-rotating weakly bound 40Ca–n He2 triatomic complexes. Two kind of systems are discussed: bosonic (n = 4) and fermionic (n = 3) complexes at its singlet state (nuclear spin S = 0). Three different coordinate systems and methods have been used to solve the relevant Schrödinger equation:...
Article
A path integral Monte Carlo method has been used to study small (4He)N–Rb2(3Σu+) complexes at low temperatures. We focus our investigation on the range 1 K ⩽ T ⩽ 2 K for aggregates of different sizes containing between 10 and 40 helium atoms. The extremely weak He–Rb2 interaction, with a shallower potential depth and a longer equilibrium bond lengt...
Article
Full-text available
We report here ((4)He)(N)-Rb(2)((3)Σ(u)) complexes, 2 ≤ N ≤ 20, analysed through a quantum diffusion Monte Carlo stochastic approach. The calculations show that the spin stretched dimer molecule is bound outside the pure He sub-complex, due to the stronger He-He potential as compared with the He-Rb(2) interaction, while the rare gas atom moiety pre...
Article
A new full-dimension potential energy surface of the three-body He-Rb₂(³Σ(u)(+)) complex and a quantum study of small (⁴He)(N)-Rb₂(³Σ(u)(+)) clusters, 1 ≤ N ≤ 4, are presented. We have accurately fitted the ab initio points of the interaction to an analytical form and addressed the dopant's vibration, which is found to be negligible. A Variational...
Article
Full-text available
In this paper, we study the energy and geometric properties of Cs2(3Σu)–(4He)N clusters, 2≤N≤20, N even, through a diffusion Monte Carlo methodology. Considering the results for doped clusters in which the He–impurity interaction dominates over the He–He one, our aim is to investigate the case when this assumption is not fulfilled anymore and the h...
Article
We present in this work the study of small (4)He(N)-Cs(2)((3)Σ(u)) aggregates (2 ≤ N ≤ 30) through combined variational, diffusion Monte Carlo (DMC), and path integral Monte Carlo (PIMC) calculations. The full surface is modeled as an addition of He-Cs(2) interactions and He-He potentials. Given the negligible strength and large range of the He-Cs(...
Article
In this work, we investigate the existence of transition state resonances on atom-diatom reactive collisions from a time-dependent perspective, stressing the role of quantum trajectories as a tool to analyze this phenomenon. As it is shown, when one focusses on the quantum probability current density, new dynamical information about the reactive pr...
Article
We study in this work the quantum scattering between a helium atom and a LiH- molecule at low and ultralow energies. For the noble gas we have considered the two natural isotopes 3He, 4He, plus a “mock” 3.5He. Our aim is to clarify the role played by the isotopic changes of the mass in the buffer gas (in this case, helium) during collision events w...
Article
Full-text available
In this paper, we carry out variational Monte Carlo and diffusion Monte Carlo (DMC) calculations for Li(2)((1)Sigma(g) (+))((4)He)(N) and Li(2)((3)Sigma(u) (+))((4)He)(N) with N up to 30 and discuss in detail the results of our computations. After a comparison between our DMC energies with the "exact" discrete variable representation values for the...
Article
We present in this work a new computational code for the quantum calculation of integral cross sections for atom–molecule (linear) scattering processes. The atom is taken to be structureless while the molecule can be in its singlet, doublet, or triplet spin states and can be treated as either a rigid rotor or a rovibrational target. All the relevan...
Article
Ab initio computed interaction forces are employed to describe the microsolvation of the A+2(2Sigma) (A=Li, Na, K) molecular ion in 4He clusters of small variable size. The minimum energy structures are obtained by performing energy minimization based on a genetic algorithm approach. The symmetry features of the collocation of solvent adatoms aroun...
Article
Full-text available
A recently developed quantum-chemistry-like methodology to study molecules solvated in atomic clusters is applied to the ICl (iodine chloride) polar diatomic molecule immersed in clusters of He atoms. The atoms of the solvent clusters are treated as the 'electrons' and the solvated molecule as a structured 'nucleus' of the combined solvent-solute s...
Article
We present here an implementation of a combined variational and diffusion Monte Carlo (VMC and DMC) procedure that we have recently successfully used in describing the `solvation' of molecular and atomic ions in small He clusters. We report the details of our numerical procedure which may use both pure Metropolis sampling and Biased (Langevin) samp...
Article
The intermolecular forces between atoms and molecules are of great importance in studies of solids, liquids and clusters. Our current studies serve to bridge the gap between small cluster and large cluster limit.
Chapter
Van der Waals complexes formed by a bromine molecule and one or several He atoms are analyzed from first principles. Multidimensional potential energy surfaces and the structure and dynamics of Br2-(He)N clusters, of increasing size N, are presented and discussed.
Article
A quantum-chemistry-like methodology developed recently to study molecules solvated in atomic clusters is reviewed, and the results of its application to diatomic molecules immersed in helium clusters are presented and discussed. The methodology is based on treating the atoms of the solvent cluster as the “electrons” and the solvated molecule (“BC”...
Article
Full-text available
Energies and structures of 4 He N -IClX complexes, N 30, are determined within the framework of a recently developed Hartree-like approach Phys. Rev. A 71, 033203 2005, in which the He atoms play the role of the electrons and the I and Cl atoms play the role of the nuclei. The potential energy of the system is represented as a sum of the He-ICl tri...
Article
Weakly bound complexes of a diatomic molecule and one or several rare gas atoms are analyzed from first principles. Focusing the study on Br2-(He)N clusters and increasing the size N, their relevant electronic potential energy surfaces, structure and photodynamics, are presented and discussed.
Article
The Born-Oppenheimer potential energy surface for the Br2(X) molecule interacting with a varying number of 4He bosons is constructed following two different schemes which employ either a full ab initio evaluation of the Br2-He interaction forces or an estimate of the latter through an empirical model. Both descriptions are employed by carrying out...
Article
Full-text available
Energies and density distributions of the helium atoms in Brâ(X)-(⁴He){sub N} clusters are calculated using a quantum 'Hartree-like' approach in which the dopant molecule and the ⁴He atoms play the role of the nuclei and electrons, respectively, of the original Hartree formulation. A detailed generalization of the methodology is presented. The...
Article
Full-text available
The aim of this paper is to elucidate the role played by the bosonic/fermionic character of N He atoms solvating a Br2(X) molecule. To this end, an adiabatic model in the molecular stretching coordinate is assumed and the ground energy levels of the complexes are searched by means of Hartree (or Hartree-Fock) Quantum Chemistry calculations for 4He...
Article
Full-text available
The role played by bosonic or fermionic character of Helium atoms surrounding a Bromine molecule was analyzed by using Raman spectra simulations. It was found that a single narrow peak occurred for the case of a pure bosonic He cluster. It was observed that a broad structure emerged from the overlap of several peaks corresponding to different multi...
Article
Full-text available
Instituto de Matemáticas y Física Fundamental (CSIC) Serrano 123, E-28006-Madrid (España) Resumen: En este trabajo, se ha simulado las transiciones de una molécula diatómical dentro de agregados bosónicos o fermiónicos de helio a muy bajas temperaturas. Para ello se ha utilizado una metodología de tipo químico-cuántico donde, una vez sustituidas la...

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