Publications (112) View all
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Article: Stability of Intermediate States for Ethylene Epoxidation on Ag-Cu Alloy Catalyst: A First-Principles Investigation
J. Phys. Chem. C. 01/2011; 115:10073. -
Article: Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
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ABSTRACT: Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn Source Package for Research in Electronic Structure, Simulation, and Optimization". It is freely available to researchers around the world under the terms of the GNU General Public License. Quantum ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively-parallel architectures, and a great effort being devoted to user friendliness. Quantum ESPRESSO is evolving towards a distribution of independent and inter-operable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes. Comment: 36 pages, 5 figures, resubmitted to J.Phys.: Condens. Matter06/2009; -
Article: Thermodynamics properties of ferropericlase
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ABSTRACT: The thermodynamics properties of ferropericlase (Mg(1-x)FexO, xFe ~ 0.19), have been investigated by first principles using a combination of newly developed techniques designed to address materials of such complexity. The strongly correlated nature of ferrous iron has been successfully addressed previously in static calculations by using a first principles LDA+U approach. However, investigation of thermodynamics properties of the solid solution presents further challenges, particularly the inclusion of vibrational effects without which results are not predictive. We have developed a vibrational virtual crystal model (VVCM) to address this issue. The acoustic velocities of the VVCM are, by construction, precisely the same as those of the real solid solution. We present here unusual anomalies on the thermodynamics properties caused by the spin crossover transition.AGU Spring Meeting Abstracts. 04/2009; -1:04. -
Article: The Ni3Al(111) surface structure: experiment and theory
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ABSTRACT: The structure of the Ni3Al(111) terminal layers has been studied by means of x-ray photoelectron diffraction and density functional theory. The analysis of the diffraction patterns, combined with multiple-scattering simulations, yields structural parameters which are in good agreement with the ab initio theoretical results. We find that the first-layer Al atoms move outwards with respect to the Ni atom plane, as previously found by low energy electron diffraction experiments and ab initio calculations. The experimentally (theoretically) determined distance between the outermost three layers is reduced by 0.07 ± 0.07 Å (0.06 ± 0.01 Å) and by 0.04 ± 0.08 Å (0.01 ± 0.01 Å) for the first-to-second-layer and second-to-third-layer distances with respect to the bulk value, respectively.Journal of Physics Condensed Matter 04/2008; 20(19):195223. · 2.55 Impact Factor -
Article: Highly under-coordinated atoms at Rh surfaces: interplay of strain and coordination effects on core level shift
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ABSTRACT: The electronic structure of highly under-coordinated Rh atoms, namely adatoms and ad-dimers, on homo-metallic surfaces has been probed by combining high-energy resolution core level photoelectron spectroscopy and density functional theory calculations. The Rh3d5/2 core level shifts are shown to be proportional to the number of Rh nearest-neighbours (n = 3, 4 and 5). A more refined analysis shows that the energy position of the different core level components is correlated with the calculated changes of the individual inter-atomic bond length and to the energy changes of the d-band centre, which is known to be a reliable descriptor of local chemical reactivity.New Journal of Physics 05/2007; 9(5):143. · 4.18 Impact Factor
