0470820 - FZÚ 2017 RIV DE eng J - Journal Article
Janiš, Václav - Kolorenč, Jindřich
Conserving approximations for response functions of the Fermi gas in a random potential.
European Physical Journal B. Roč. 89, č. 7 (2016), 1-12, č. článku 170. ISSN 1434-6028. E-ISSN 1434-6036
R&D Projects: GA ČR GA15-14259S
Institutional support: RVO:68378271
Keywords : strong disorder * charge diffusion * Ward indentities * vertex corrections * diffusion constant * thermodynamic consistency
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 1.436, year: 2016 ; AIS: 0.449, rok: 2016
DOI: https://doi.org/10.1140/epjb/e2016-70188-1

One- and two-electron Green functions are simultaneously needed to determine the response functions of the electron gas in a random potential. Reliable approximations must retain consistency between the two types of Green functions expressed via Ward identities so that their output is compliant with macroscopic symmetries and conservation laws. Such a consistency is not directly guaranteed when summing nonlocal corrections to the local (dynamical) mean field. We show how the full Ward identity can generically be implemented in the diagrammatic approach without breaking the analytic properties of the self-energy. We use the low-energy asymptotics of the conserving two-particle vertex determining the singular part of response and correlation functions to derive an exact representation of the diffusion constant in terms of Green functions of the perturbation theory. We then calculate explicitly the leading vertex corrections to the mean-field diffusion constant.

Permanent Link: http://hdl.handle.net/11104/0268370