Ab initio study of polarons in the alkali halides

A charge carrier propagating through a crystal induces distortions in the lattice via the electron-phonon interaction. The quasiparticle formed by the carrier and the lattice distortion is referred to as a polaron. Recent advances have enabled the calculation of small and large polarons on the same footing from first principles [Phys. Rev. Lett. 122, 246403 (2019); Phys. Rev. Lett. 129, 076402 (2022)]. In this talk, we present a systematic application of these methods to a broad family of materials that span a very wide range of electron-phonon interaction strengths, the alkali halides. We show that these compounds consistently host large electron polarons and small hole polarons. By investigating how the coupling mechanism, formation energy, and polaron radius depend on materials properties such as dielectric constants, band gaps, and effective masses, we establish general scaling laws and we identify the validity range of standard polaron models.