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arXiv · 1111.6166

Drude and Superfluid Weights in Extended Systems: the Role of Discontinuities and $δ$-peaks in the One and Two-Body Momentum Densities

Balázs Hetényi
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Abstract

The question of conductivity is revisited. Using the total momentum shift operator to construct the perturbed many-body Hamiltonian and ground state wave function the second derivative of the ground state energy with respect to the perturbing field is expressed in terms of the one and two-body momentum densities. The distinction between the adiabatic and envelope function derivatives, hence that between the Drude and superfluid weights can be introduced in a straightforward manner. It is shown that a discontinuity in the momentum density leads to a contribution to the Drude weight, but not the superfluid weight, however a $δ$-function contribution in the two-body momentum density (such as in the BCS wave-funtion) contributes to both quantities. The connection between the discontinuity in the momentum density and localization is also demonstrated.

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Balázs Hetényi. 2012-01-02. Drude and Superfluid Weights in Extended Systems: the Role of Discontinuities and $δ$-peaks in the One and Two-Body Momentum Densities. https://doi.org/10.1143/jpsj.81.023701

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