RESEARCH INTERESTS

My work centers around the study of the properties of materials by means of computational methods. Computational Materials Science has emerged in recent years as a very useful complement to the traditional "experimental" and "theoretical" approaches. Since we know the basic laws that determine the behavior of the constituents of matter (electrons and nuclei at our usual energy scales), we can, in principle, simulate their behavior on a computer. If our computer program implements faithfully the relevant laws, and we can solve the resulting equations with an appropriate level of accuracy, we have a realistic "ultimate" model of the properties of the materials, and can perform "computer experiments". These are extremely useful in a variety of circumstances:

To complement experimental information in those cases in which it is difficult or even impossible to obtain (think of minerals at high pressures and temperatures), or too time-consuming or impractical (large-scale exploration of different compositions and structures in search of optimal properties, for example).
Since the computer is in essence the perfect control machine, we can be sure that we deal precisely with the right conditions under which we want to study our system. For example, when dealing with defects in semiconductors, it is very difficult to prepare experimentally a sample with "only vacancies", or "only interstitials". On the computer we can work with isolated defects and study their properties.
The computer works during the simulation with data (wave functions, atomic displacements, etc) that contains information useful to parametrize simpler models. For instance, using the wave functions, we can obtain the parameters appropriate for a simplified view ("Ising model") of the magnetic properties of a material.

Follow this link to download the material from a lecture about the uses of simulation in materials science.

During my career I have been lucky enough to explore a wide variety of systems (minerals, semiconductors, ferroelectrics...) and computational techniques (ab-initio simulations, Monte Carlo methods...), and to work with very talented people.

Recent work includes:

"Crystal structure determination of karibibite, an Fe+3 arsenite, using electron diffraction tomography", F. Colombo, E. Mugnaioli, O. Vallcorba, A. Garcia, A. Goni, J. Rius, in press in Mineralogical Magazine (2016)
"Improvements on non-equilibrium and transport Green function techniques: the next-generation TranSiesta", N Papior, N Lorente, T Frederiksen, A Garcia, M Brandbyge Computer Physics Communications, published online 11 October 2016, DOI:10.1016/j.cpc.2016.09.022
"Quasiparticle spectra of 2H-NbSe2: Two-band superconductivity and the role of tunneling selectivity", Y Noat, J. A Silva-Guillen, T Cren, V Cherkez, C Brun, S Pons, F Debontridder, D Roditchev, W Sacks, L Cario, P Ordejon, A Garcia, E Canadell, Phys. Rev. B 92, 134510 (2015). DOI:10.1103/PhysRevB.92.134510
"SIESTA-PEXSI: massively parallel method for efficient and accurate ab initio materials simulation without matrix diagonalization", L. Lin, A. Garcia, G. Huhs, C. Yang, J. Phys. Cond. Matt. 26, 305503 (2014). DOI:10.1088/0953-8984/26/30/305503
"Aluminum ordering and clustering in Al-rich synthetic phlogopite: 1H 29Si CPMAS HETCOR spectroscopy and atomistic calculations", R. Langner, M. Fechtelkord, A. Garcia, E. J. Palin, and J. Lopez-Solano, American Mineralogist 97, 341-352 (2012). DOI: 10.2138/am.2012.3840
"Superlattice pseudo-uniform orderings as modulated structures: Stripe and checkerboard arrangements", S. Gonzalez, J.M. Perez-Mato, A. Garcia, L. Elcoro, Physical Review B 84, 184106 (2011). DOI: 10.1103/PhysRevB.84.184106
"Huge Interface Dipole Moments Induced by Buckybowls on Metal Surfaces", T. Bauert, L. Zoppi, G. Koller, A. Garcia, K. Baldridge, K-H. Ernst, Jour. Phys. Chem. Lett. 2, 2805-2809 (2011). DOI: 10.1021/jz2012484
"An efficient implementation of a QM-MM method in SIESTA", C. F. Sanz-Navarro, R. Grima, A. Garcia, E. A. Bea, A. Soba, J.M. Cela, and P. Ordejon, Theoretical Chemistry Accounts 128, 825-833 (2011). DOI: 10.1007/s00214-010-0816-5
"Self-organized Ce_{1-x}Gd_xO_{2-y} nanowire networks with ultrafast coarsening driven by attractive elastic interactions", M. Gibert, P. Abellan, A. Benedetti, T. Puig, F. Sandiumenge, A. Garcia, X. Obradors, Small, 6, 2716-2724 (2010). DOI: 10.1002/smll.201001237
"An efficient computational method for use in structural studies of crystals with substitutional disorder", R. Poloni, J. Iniguez, A. Garcia, and E. Canadell, Journal of Physics-Condensed Matter 22, 415401 (2010). DOI: 10.1088/0953-8984/22/41/45401
"Dependence of the lone pair of bismuth on coordination environment and pressure: An ab initio study on Cu4Bi5S10 and Bi2S3", L. A. Olsen, J. Lopez-Solano, A. Garcia, T. Balic-Zunic, E. Makovicky, Journal of Solid State Chemistry 183, 2133-2143 (2010). DOI: 10.1016/j.jssc.2010.07.022

I devote part of my time to the development of computational methods (mostly on the SIESTA project).