Ricardo Grau-Crespo

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We have employed atomistic simulation techniques to investigate the thermodynamics of mixing in the solid solutions of calcite (CaCO(3)) and rhodochrosite (MnCO(3)). Our calculations show that the fully disordered solid solution has positive enthalpies of mixing for the entire range of compositions, which confirm recent experiments. The consideration of a(More)
We use density functional theory calculations with Hubbard corrections (DFT+U) to investigate electronic aspects of the interaction between ceria surfaces and gold atoms. Our results show that Au adatoms at the (111) surface of ceria can adopt Au(0), Au(+) or Au(-) electronic configurations depending on the adsorption site. The strongest adsorption sites(More)
Modelling of disorder in organic crystals is highly desirable since it would allow thermodynamic stabilities and other disorder-sensitive properties to be estimated for such systems. Two disordered organic molecular systems are modeled using a symmetry-adapted ensemble approach, in which the disordered system is treated as an ensemble of the configurations(More)
Modification of graphene to open a robust gap in its electronic spectrum is essential for its use in field effect transistors and photochemistry applications. Inspired by recent experimental success in the preparation of homogeneous alloys of graphene and boron nitride (BN), we consider here engineering the electronic structure and bandgap of C2xB1-xN1-x(More)
We present the results of a density functional theory investigation of the surfaces of rutile-like vanadium dioxide, VO(2)(R). We calculate the surface energies of low Miller index planes and find that the most stable surface orientation is the (110). The equilibrium morphology of a VO(2)(R) particle has an acicular shape, laterally confined by (110) planes(More)
The crystal structure of the iron oxide γ-Fe₂O₃ is usually reported in either the cubic system (space group P4(3)32) with partial Fe vacancy disorder or in the tetragonal system (space group P4(1)2(1)2) with full site ordering and c/a≈3. Using a supercell of the cubic structure, we obtain the spectrum of energies of all the ordered configurations which(More)
The renewed interest in magnetite (Fe3O4) as a major phase in different types of catalysts has led us to study the oxidation-reduction behaviour of its most prominent surfaces. We have employed computer modelling techniques based on the density functional theory to calculate the geometries and surface free energies of a number of surfaces at different(More)
The electronic structure and oxidation state of atomic Au adsorbed on a perfect CeO(2)(111) surface have been investigated in detail by means of periodic density functional theory-based calculations, using the LDA+U and GGA+U potentials for a broad range of U values, complemented with calculations employing the HSE06 hybrid functional. In addition, the(More)
a r t i c l e i n f o a b s t r a c t For many years ab initio electronic structure calculations based upon density functional theory have been one of the main application areas in high performance computing (HPC). Typically, the Kohn– Sham equations are solved by minimisation of the total energy functional, using a plane wave basis set for valence(More)
Density functional theory calculations indicate that the incorporation of V into Ti lattice positions of rutile TiO(2) leads to magnetic V(4+) species, but the extension and sign of the coupling between dopant moments confirm that ferromagnetic order cannot be reached via low-concentration doping in the non-defective oxide. Oxygen vacancies can introduce(More)