Thermodynamic Stability at the Two-Particle Level

Abstract

We show how the stability conditions for a system of interacting fermions that conventionally involve variations of thermodynamic potentials can be rewritten in terms of one- and two-particle correlators. We illustrate the applicability of this alternative formulation in a multi-orbital model of strongly correlated electrons at finite temperatures, inspecting the lowest eigenvalues of the generalized local charge susceptibility in proximity of the phase-separation region. Additionally to the conventional unstable branches, we address unstable solutions possessing a positive, rather than negative compressibility. Our stability conditions require no derivative of free energy functions with conceptual and practical advantages for actual calculations and offer a clear-cut criterion for analyzing the thermodynamics of correlated complex systems.

8+8 pages, 3+1 figures

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Cited by in corpus (7)

• Compressing the two-particle Green's function using wavelets: Theory and application to the Hubbard atom
• Effective enhancement of the electron-phonon coupling driven by nonperturbative electronic density fluctuations
• Non-Perturbative Feats in the Physics of Correlated Antiferromagnets
• Suppression of the charge fluctuations by nonlocal correlations close to the Mott transition
• Origin of misleading convergence in self-consistent many-electron theories: Fundamental aspects and practical implications
• Non-perturbative effects of short-range spatial correlations at the two-particle level
• Specific heat and density anomaly in the Hubbard model