Publications

2026

• Designing explicit functionals for the charge density in terms of a potential
  
  • Güneş Muhammed
  • Aouina Ayoub
  • Gorelov Vitaly
  • Gatti Matteo
  • Reining Lucia
  Physical Review B, American Physical Society, 2026, 114 (12), pp.125120. One of the most powerful strategies to address properties of real many-body systems is to incorporate data obtained for models, for example, to use data of the homogeneous electron gas in order to build the local density approximation for the Kohn-Sham exchange-correlation potential. In the present work, we examine to what extent we can use model data to design functionals directly for observables of materials. In particular, we study different approximations for the charge density of real inhomogeneous materials expressed as a simple, explicit functional of a given Kohn-Sham potential, using as a central building block the Lindhard density-density response function of the homogeneous electron gas. Our increasingly realistic set of approximations includes a fully nearsighted expression equivalent to the Thomas-Fermi approximation, functional Taylor expansions, and different approximations to the connector theory developed by A. Aouina et al. [npj Comput. Mater. 11, 242 (2025)]. In all cases, the charge density is obtained without ever solving the Kohn-Sham Schrödinger equation. Results for cubic helium, a prototypical strongly inhomogeneous material, as well as the covalent semiconductor silicon and metallic aluminum, systematically improve with higher levels of approximation. At the present stage, the results may be used for qualitative discussions or as an optimized starting point for a self-consistent Kohn-Sham cycle. More generally, their quality indicates that this is a promising route to obtain functional expressions for observables that are relatively simple to calculate and to analyze. (10.1103/zztt-z1wj)
  DOI : 10.1103/zztt-z1wj
• Electron injection and acceleration into laser-driven wakefield from a solid overdense plasma target
  
  • Caetano de Sousa M.
  • Marini S.
  • Grech M.
  • Brunner S.
  • Riconda C.
  • Raynaud M.
  Physics of Plasmas, American Institute of Physics, 2026, 33 (8), pp.083103. A laser–plasma acceleration scheme combining electron extraction from a solid overdense target with wakefield acceleration in an adjacent underdense plasma region is presented. A laser pulse excites a diffracted electromagnetic wave at the overdense plasma interface, extracting and pre-accelerating electrons, which are then injected into laser-driven wakefield cavities in the underdense plasma. A parametric study identifies key conditions enabling efficient electron injection and energy gain in this two-stage acceleration configuration. Two-dimensional particle-in-cell simulations performed with the Smilei code show that the proposed scheme produces electron bunches with a tunable trade-off between charge, energy, and beam quality at laser intensity <i>I₀</i>λ$_0^2$ ≃ 3.4×10¹⁹ W μm²/cm² (λ₀ = 0.8 μm). According to the parameters used, the electron beam is accelerated to peak energies of ∼150−250 MeV with an estimated charge in 3D of ∼50−400 pC integrated over the full width at half maximum energy range, and ∼100−1900 pC with energies above 50 MeV. (10.1063/5.0346116)
  DOI : 10.1063/5.0346116
• Defect characterization of the SiO\textsubscript2/Si interface investigated by drift-assisted positron annihilation lifetime spectroscopy
  
  • Mayerhofer Michael
  • Lee Kangho
  • Duesberg Georg S
  • Dollinger Günther
  • Dickmann Marcel
  • Helm Ricardo
  • Egger Werner
  • Corbel Catherine
  • Sperr Peter
  • Butterling Maik
  • Wagner Andreas
  • Liedke Maciej Oskar
  • Hirschmann Eric
  • Mitteneder Johannes
  Nanomaterials, MDPI, 2026, 16 (3), pp.156. (10.3390/nano16030156)
  DOI : 10.3390/nano16030156
• Theoretical description of the energy flow mechanisms in photoexcited semiconductors
  
  • Sen Raja
  • Vast Nathalie
  • Sjakste Jelena
  Proceedings of SPIE, the International Society for Optical Engineering, SPIE, The International Society for Optical Engineering, 2026, 14077, pp.21. In this work, we discuss some aspects of the density functional theory-based description of the energy transfer from photoexcited carriers to phonons, using the example of the energy transfer between photoexcited holes and phonons in Germanium. Recently, this approach allowed us to interpret the measured dynamics of the heating of Raman-active modes on a few-ps timescale in Ge, which was investigated with time-resolved Raman spectroscopy. We discuss in particular the limits of applicability of the widely used self-energy approximation, for the specific case of very hot carriers and of transient spectroscopy studies. (10.1117/12.3099911)
  DOI : 10.1117/12.3099911