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arXiv · 1705.09071

Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation

Kosuke Hamada·Tatsuya Kaneko·Shohei Miyakoshi·Yukinori Ohta
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Abstract

We comparatively study the excitonic insulator state in the extended Falicov-Kimball model (EFKM, a spinless two-band model) on the two-dimensional square lattice using the variational cluster approximation (VCA) and the cluster dynamical impurity approximation (CDIA). In the latter, the particle-bath sites are included in the reference cluster to take into account the particle-number fluctuations in the correlation sites. We thus calculate the particle-number distribution, order parameter, ground-state phase diagram, anomalous Green's function, and pair coherence length, thereby demonstrating the usefulness of the CDIA in the discussion of the excitonic condensation in the EFKM.

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Kosuke Hamada, Tatsuya Kaneko, Shohei Miyakoshi, Yukinori Ohta. 2017-05-25. Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity Approximation. https://doi.org/10.7566/jpsj.86.074709

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