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Dynamical mean field theory: In practice
N.S.Vidhyadhiraja Theoretical sciences unit, JNCASR, Bangalore.
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Outline Brief review of DMFT Impurity solvers
Iterated perturbation theory Self energy calculation Symmetric case Asymmetric case Output – Green’s functions, DOS, Transport and thermodynamics Numerical implementation
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Dynamical mean field theory Implementation
∑(z)
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Impurity solvers Iterated perturbation theory (IPT)
Local moment approach Non-crossing approximation Exact diagonalization Quantum Monte Carlo Numerical Renormalization group Density-Matrix Renormalization group.
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Iterated perturbation Theory (IPT)
Iterated perturbation theory at half-filling: Self-energy is just the second order correction built out of Hartree propagators.
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Equations (1.5), (1.6) and (1.7) do not assume p-h symmetry so they can be used for the asymmetric case as well.
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References for IPT:
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Physical observables Green’s functions G(ω)
Spectral function A(ω)= -Im(G(ω))/π Electronic density of states Re(G-1(ω))=0 gives Quasiparticle energies. Z=[{1 - ∂(Re(∑))/∂ω)}ω 0]-1 is the quasiparticle weight and Z-1 is the mass renormalization.
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Transport Quantities Linear response – Kubo formula
Find the current-current correlation function. Optical Conductivity DC Conductivity = ω 0 limit of Optical Conductivity.
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Numerical implementation
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