Speaker
Description
The standard Fröhlich (one phonon band, non-degenerate electronic state, isotropic) model is a workhorse for the large polaron community, used for decades.
Recently [1], a generalization of this Fröhlich model (multiple phonon bands, degenerate electronic states, anisotropic) has been introduced.
I will present a high-throughput analysis of the outcome of these two models [2] for a large set of 1260 materials, also analyzing their domain of validity, when fed with first-principles data.
Among this extended dataset most materials host perturbative large polarons, but there are many instances that are non-perturbative and/or localize on distances of a few bond lengths.
A variety of behaviors is found, with statistical characterization of these for this large set of materials.
Then, I will present a first-principles study of self-trapped polaron formation in paradigmatic polar
semiconductors and insulators using the variational polaron equations framework, that does not rely on supercells [3]. The variational approach enables the identification of multiple polaronic
states and supports the analysis of polarons with arbitrarily large spatial extent via energy filtering. The potential energy
surfaces of the resulting polarons exhibit multiple local minima, reflecting distinct, symmetry-broken
polaronic configurations in systems with degenerate band edges.
[1] A. Miglio, V. Brousseau-Couture, E. Godbout, G. Antonius, Y.-H. Chan, S.G. Louie, M. Côté, M. Giatomassi, and X. Gonze. npj Computational Materials 6, 167 (2020).
[2] P.M.M.C. de Melo, J.C. de Abreu, B. Guster, M. Giantomassi, Z. Zanolli, X. Gonze and M. Verstraete, npj Computational Materials 147, 9 (2023).
[3] V. Vasilchenko, M. Giantomassi, S. Poncé and X. Gonze, Phys. Rev. 112, 014314 (2025).