2002/03/31 by V. Janis, V. Jani, J. Kolorenc +3 · 21 citations
Engineering · Materials Science · Physics and Astronomy · #Computer science #Condensed matter physics #Conductivity #Current (fluid) #Current density #Data mining #Diffusion #Einstein #Einstein relation #Electrical resistivity and conductivity #Electron #Engineering #Materials science #Organic and Molecular Conductors Research #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Relation (database) #Thermodynamics #cond-mat.dis-nn #cond-mat.str-el
paper · pdf · doi:10.1140/epjb/e2003-00258-4
published in The European Physical Journal B 35(1), 77-91 (Springer Science+Business Media) · 16 pages, REVTeX4, 6 EPS figures
arxiv created 2003/01/03 · openalex publication_date 2003/09/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study consequences of gauge invariance and charge conservation of an electron gas in a strong random potential perturbed by a weak electromagnetic field. We use quantum equations of motion and Ward identities for one- and two-particle averaged Green functions to establish exact relations between density and current response functions. In particular we find precise conditions under which we can extract the current-current correlation function from the density-density correlation function and vice versa. We use these results in two different ways to extend validity of a formula associating the density response function with the electrical conductivity from semiclassical equilibrium to quantum nonequilibrium systems. Finally we introduce quantum diffusion via a response relating the current with the negative gradient of the charge density. With the aid of this response function we derive a quantum version of the Einstein relation and prove the existence of the diffusion pole in the zero-temperature electron-hole correlation function with the the long-range spatial fluctuations controlled by the static diffusion constant.