Speaker
Description
First-principles approaches for phonon-limited electronic transport are typically based on many-body perturbation theory [1] and thus rely on the validity of a quasi-particle picture for phonons and electrons. However, both these pictures can become questionable in strongly anharmonic systems [2,3]. We overcome this hurdle by combining ab initio molecular dynamics (aiMD) calculations with the Kubo-Greenwood (KG) formalism [4]. This non-perturbative, stochastic method allows us to account for all orders of anharmonic and vibronic couplings in the calculation of carrier mobilities. We discuss the implementation of this formalism in the ab initio material simulation package FHI-aims [5] and the strategy to extrapolate to the direct current limit [6]. Furthermore, to analyze the impact of strong electron-nuclei interactions on the electronic structure, we also developed an efficient band unfolding method for linear combination of atomic-centered orbital (LCAO) basis sets [7], enabling us to define a non-perturbative, temperature-dependent electronic spectral function. Finally, we demonstrate the capabilities of these methods by calculating and analyzing the temperature-dependent electron mobility of the strongly anharmonic oxide perovskites SrTiO3 and BaTiO3 across a wide range of temperatures [8].
References
[1] S. Poncé, W. Li, S. Reichardt, and F. Giustino, First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional materials, Rep. Prog. Phys. 83, 036501, 2024; https://doi.org/10.1088/1361-6633/ab6a43
[2] F. Knoop, T.A.R. Purcell, M. Scheffler, and C. Carbogno, Anharmonicity in Thermal Insulators: An Analysis from First Principles, Phys. Rev. Lett. 130, 236301 2023; https://doi.org/10.1103/PhysRevLett.130.236301
[3] M. Zacharias, M. Scheffler, and C. Carbogno, Fully anharmonic nonperturbative theory of vibronically renormalized electronic band structures, Phys. Rev. B 102, 045126, 2020; https://doi.org/10.1103/PhysRevB.102.045126
[4] B. Holst, M. French, and R. Redmer, Electronic transport coefficients from ab initio simulations and application to dense liquid hydrogen, Phys. Rev. B 83, 235120, 2011; https://doi.org/10.1103/PhysRevB.83.235120
[5] V. Blum, R. Gehrke, F. Hanke, P. Havu, V. Havu, X. Ren, K. Reuter, and M. Scheffler, Ab initio molecular simulations with numeric atom-centered orbitals, Comp. Phys. Comm. 180, 2175-2196, 2009; https://doi.org/10.1016/j.cpc.2009.06.022
[6] M. French, G. Röpke, M. Schörner, M. Bethkenhagen, M. P. Desjarlais, and R. Redmer, Electronic transport coefficients from density functional theory across the plasma plane, Phys. Rev. E 105, 065204, 2022; https://doi.org/10.1103/PhysRevE.105.065204
[7] J. Quan, N. Rybin, M. Scheffler, and C. Carbogno, in preperation.
[8] J. Quan, C. Carbogno, and M. Scheffler, Carrier Mobility of Strongly Anharmonic Materials from First Principles, arXiv 2408.12908, 2024; https://doi.org/10.48550/arXiv.2408.12908
