Description
Our group works in the development and application of state-of-the-art ab-initio methods to systems of both fundamental and technological interest. We are a part of the Institut Lumière Matière, situated at the Université Claude Bernard Lyon 1, in Lyon, France. We are also members of the European Theoretical Spectroscopy Facility. We are also sponsored by the following institutions:
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Highlights (all highlights)
April 30, 2013
Phonon renormalization of the band-gap of semiconductors
The self-consistent GW band gaps are known to be significantly overestimated. We show that this overestimation is, to a large extent, due to the neglect of the contribution of the lattice polarization to the screening of the electron-electron interaction. To solve this problem, we derive within the GW formalism a generalized plasmon-pole model that accounts for lattice polarization. The resulting GW self-energy is used to calculate the band structures of a set of binary semiconductors and insulators. The lattice contribution always decreases the band gap. The shrinkage increases with the size of the longitudinal-transverse optical splitting and it can represent more than 15% of the band gap in highly polar compounds, reducing the band-gap percentage error by a factor of three.
This work has just been accepted for publication in
Phys. Rev. Lett.
March 08, 2013
Topological insulators in ternary compounds with honeycomb lattice
It was recently predicted, on purely theoretical bases, the existence of a new family of topological insulators. This family can be seen as a relative of graphite and crystallizes in a honeycomb lattice (space group P63/mmc, #194). Keeping this structure, many ternary combinations were tried by replacing the three chemical elements. However, the honeycomb structure is dynamically unstable for some of the proposed materials, including the key example LiAuSe, whose true ground state (shown in the picture) does not display topological insulator properties.
This work has just been accepted for publication in
Phys. Rev. Lett.
February 20, 2013
Low-Energy Polymeric Phases of Alanates
Low-energy structures of
alanates are currently known to be described by patterns of isolated, nearly ideal tetrahedral [AlH4] anions and metal cations.
We discover, with our collaborators in Basel, that the novel
polymeric motif recently proposed for LiAlH4 plays a dominant role in a series of alanates, including LiAlH4, NaAlH4,
KAlH4, Mg(AlH4)2, Ca(AlH4)2 and Sr(AlH4)2. In particular, most of the low-energy structures discovered for the whole series are
characterized by networks of corner-sharing [AlH6] octahedra, forming wires and/or planes throughout the materials. Finally,
for Mg(AlH4)2 and Sr(AlH4)2, we identify two polymeric phases to be lowest in energy at low temperatures.
This work has just been accepted for publication in
Phys. Rev. Lett.
January 09, 2013
European Physics Journal B
Miguel A. L. Marques and Silvana Botti are now editors of the European Physics Journal B.
December 17, 2012
2nd Lyon Informal School on Ab Initio Methods
We just had our 2nd Lyon Informal School on Ab Initio Methods on the 12th and 13th of December 2012. This was a crash course on the ab initio methods used in our group. It was quite dense and the level went up very rapidly, but we hope that our students got a glimpse on modern condensed matter theory. The program can be found here.