A generalized perspective on non-perturbative linked-cluster expansions

Coester K, Clever S, Herbst F, Capponi S, Schmidt KP (2015)

Publication Status: Published

Publication Type: Journal article

Publication year: 2015

Journal

EPL - Europhysics Letters Institute of Physics: EPL

Publisher: EPL ASSOCIATION, EUROPEAN PHYSICAL SOCIETY

Book Volume: 110

Journal Issue: 2

DOI: 10.1209/0295-5075/110/20006

Abstract

We identify a fundamental challenge for any non-perturbative approach based on finite clusters resulting from the reduced symmetry on graphs, most importantly the breaking of translational symmetry, when targeting the properties of excited states. This can be traced back to the appearance of intruder states in the low-energy spectrum, which represent a major obstacle in quasi-degenerate perturbation theory. Here a generalized notion of cluster additivity is introduced, which is used to formulate an optimized scheme of graph-based continuous unitary transformations allowing to solve and to physically understand this major issue. Most remarkably, our improved scheme demands to go beyond the paradigm of using the exact eigenvectors on graphs. Copyright (C) EPLA, 2015

Authors with CRIS profile

Kai Phillip Schmidt Professur für Theoretische Physik

Involved external institutions

Technische Universität Dortmund DE Germany (DE) Université Toulouse III - Paul Sabatier FR France (FR)

How to cite

APA:

Coester, K., Clever, S., Herbst, F., Capponi, S., & Schmidt, K.P. (2015). A generalized perspective on non-perturbative linked-cluster expansions. EPL - Europhysics Letters, 110(2). https://dx.doi.org/10.1209/0295-5075/110/20006

MLA:

Coester, K., et al. "A generalized perspective on non-perturbative linked-cluster expansions." EPL - Europhysics Letters 110.2 (2015).

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