Numerical modelling of materials

Correlated Electrons

Post-Image

Figure 1: Spectral function of bcc iron computed in DFT+DMFT in a Brillouin zone path (see Gendron et al.). It shows the theoretical description of a photoemission spectra. Electron interactions induce widening, continuous variation of intensity (blue : low intensity, yellow : high intensity) and splitting of bands induced by exchange. On the right, integrated spectral functions are shown for t2g and eg d orbitals.

Correlated Electrons

The LMCE is interested in describing systems composed of actinides and lanthanides. These elements have localized f-orbitals, so that the electrons in these orbitals are in a restricted space and therefore strongly repel each other. These electronic interactions (also called correlations) compete with hybridization between atoms and give rise to, for example, electron localization/delocalization transitions. These effects are not described by the approximations available in density functional theory (DFT). To describe these phenomena, the DFT+U methods, as well as the combination of DFT with the dynamic mean field theory (DMFT) have been implemented in the ABINIT code. We use these advanced methods, sometimes combined with machine learning approaches, to predict structural, elastic, magnetic or phonons properties of lanthanides or actinides but also transition metals. These studies are carried out in collaboration with experimentalists in the laboratory

Phonon energy (top) and linewidth dispersions (bottom) in the Brillouin zone for a uranium molybdenum alloy. Theoretical calculations (dashed line (virtual crystal approximation) and color map (full spectral function)) are compared to experimental data (see Chaney et al.)

Figure 2:

Phonon energy (top) and linewidth dispersions (bottom) in the Brillouin zone for a uranium molybdenum alloy. Theoretical calculations (dashed line (virtual crystal approximation) and color map (full spectral function)) are compared to experimental data (see Chaney et al.)

Publications

  1. B. Amadon, First-principles DFT+ DMFT calculations of structural properties of actinides: Role of Hund’s exchange, spin-orbit coupling, and crystal structure,Phys. Rev. B 94, 115148 (2016) DOI
  2. D. Chaney, A. Castellano, A. Bosak, J. Bouchet, F. Bottin, B. Dorado, L. Paolasini, S. Rennie, C. Bell, R. Springell, G.H. Lander, Tuneable correlated disorder in alloys, Physical Review Materials 5 (3), 035004 (2021) DOI
  3. M.S.T. Noutack, G. Geneste, G. Jomard, M. Freyss First-principles investigation of the bulk properties of americium dioxide and sesquioxides, Physical Review Materials 3 (3), 035001 (2019) DOI
  4. F. Gendron, N. Cliche, B. Amadon, Role of pressure on electronic, magnetic and structural properties at iron’s Curie temperature: a DFT+DMFT study, J. Phys.: Condens. Matter 34 464003 (2022) DOI
  5. F. Bottin, R. Béjaud, B. Amadon, L. Baguet, M. Torrent, A. Castellano, J. Bouchet, Huge anharmonic effects in delta plutonium, Phys. Rev. B 109, L060304 (2024) DOI

Researchers involved

B. Amadon, R. Bejaud, F. Bottin, F. Gendron, G. Geneste, F. Jollet, M. Torrent