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SUMMARY:Many-Body Perturbation Theory: The GW Approximation - David O'Rega
 n\, TCM
DTSTART:20080307T153000Z
DTEND:20080307T160000Z
UID:TALK10638@talks.cam.ac.uk
CONTACT:James Kermode
DESCRIPTION:Christoph Friedrich and Arno Schindlmayr\, Many-Body Perturbat
 ion Theory: The GW Approximation\n\nComputational Nanoscience: Do It Yours
 elf!\, J. Grotendorst\, S. Blugel\, D. Marx (Eds.)\, John von Neumann Inst
 itute for Computing\, Julich\, NIC Series\, "Vol. 31\, pp. 335-355\, 2006"
 :http://www.fz-juelich.de/nic-series/volume31/friedrich.pdf\n\nAbstract: I
 n this lecture we present many-body perturbation theory as a method to det
 ermine quasiparticle excitations in solids\, especially electronic band st
 ructures\, accurately from first principles. The main ingredient is the el
 ectronic self-energy that\, in principle\, contains all many-body exchange
  and correlation effects beyond the Hartree potential. As its exact mathem
 atical expression is unknown\, approximations must be used in practical ca
 lculations. The GW approximation is obtained using a systematic algebraic 
 approach on the basis of Green function techniques. It constitutes an expa
 nsion of the self-energy up to linear order in the screened Coulomb potent
 ial\, which describes the interaction between the quasiparticles and inclu
 des dynamic screening through the creation of exchange-correlation holes a
 round the bare particles. The implementation of the GW approximation relie
 s on a perturbative treatment starting from density functional theory. Bes
 ides a detailed mathematical discussion we focus on the underlying physica
 l concepts and show some illustrative applications.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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