Functional Integrals for Correlated Electrons

V. I. Belinicher, Michael Chertkov

Heinz J. Schulz

Mahashweta Patra

This report is to introduce the concept of the Feynman path integral. Particular emphasis is placed on establishing the interaction between the quantum mechanical path integral, classical Hamiltonian mechanics, and classical mechanics. Functional integral in many body system has also been done. Zero temperature BCS theory has been derived using functional integral form via Hubbard Stratonovich transformation. how the Hubbard model describes the s-wave, and d-wave order parameter has been discussed here. In this report the t

Michael Potthoff

Andreas Rückriegel, Jonas Arnold, Rüdiger Krämer +1 more

The authors show here that exact functional renormalization group flow (FRG) equations for quantum systems can be derived directly within an operator formalism without using functional integrals. This simple insight opens new possibilities for applying FRG methods to models for strongly correlated electrons with projected Hilbert spaces, such as quantum spin models, the $t$-$J$ model, or the Hubbard model at infinite on-site repulsion. By representing these models in terms of Hubbard X-operators, various applications of this approach are explored.

David Sénéchal, A.–M. S. Tremblay, C. Bourbonnais