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arXiv · 1605.02373

The Functional Integral formulation of the Schrieffer-Wolff transformation

Farzaneh Zamani·Pedro Ribeiro·Stefan Kirchner
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Abstract

We revisit the Schrieffer-Wolff transformation and present a path integral version of this important canonical transformation. The equivalence between the low-energy sector of the Anderson model in the so-called local moment regime and the spin-isotropic Kondo model is usually established via a canonical transformation performed on the Hamiltonian, followed by a projection. Here we present a path integral formulation of the Schrieffer-Wolff transformation which relates the functional integral form of the partition function of the Anderson model to that of its effective low-energy model. The resulting functional integral assumes the form of a spin path integral and includes a geometric phase factor, i.e. a Berry phase. Our approach stresses the underlying symmetries of the model and allows for a straightforward generalization of the transformation to more involved models. It thus not only sheds new light on a classic problem, it also offers a systematic route of obtaining effective low-energy models and higher order corrections.

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Farzaneh Zamani, Pedro Ribeiro, Stefan Kirchner. 2016-07-07. The Functional Integral formulation of the Schrieffer-Wolff transformation. https://doi.org/10.1088/1367-2630%2F18%2F6%2F063024

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