Dual-fermions

Official Resources

• Source Repository (opendf): https://github.com/CQMP/opendf
• Source Repository (DFermion): https://github.com/huangli712/DFermion
• Paper: https://arxiv.org/abs/1507.00895
• License: GPL v3 (opendf)

Overview

"Dual Fermions" refers to a theoretical method (Dual Fermion expansion) for going beyond Dynamical Mean Field Theory (DMFT) to include non-local spatial correlations. While not a single software package, there are specific open-source implementations, most notably opendf (developed by the Center for Quantum Materials Physics) and DFermion. These codes solve strongly correlated lattice problems (like the Hubbard model) using the dual fermion diagrammatic expansion.

Scientific domain: Many-body physics, Strongly Correlated Systems, DMFT extensions
Target user community: Theoretical physicists

Capabilities (CRITICAL)

• Method: Dual Fermion (DF) diagrammatic expansion.
• Models: Single-orbital Hubbard model (opendf).
• Solvers: Uses Continuous-Time Quantum Monte Carlo (CT-QMC) as an impurity solver (often external or integrated).
• Correlations: Captures non-local spatial correlations missed by standard DMFT.
• Dimensions: Applicable to 2D square, 3D cubic lattices, etc.

Inputs & Outputs

• Input formats: Configuration files (parameters for interaction U, temperature T, chemical potential).
• Output data types: Self-energies, Green's functions, susceptibility.

Performance Characteristics

• Computationally intensive due to Monte Carlo sampling and diagrammatic summation.
• Scales with the number of diagrams/orders considered.

Application Areas

• Phase transitions in Hubbard models (e.g., antiferromagnetism).
• Pseudogap physics in cuprates.
• Non-local correlation effects.

Verification & Sources

• opendf: Verified existence on GitHub (CQMP/opendf) and published paper (Phys. Procedia).
• DFermion: Verified existence on GitHub.

Confidence: VERIFIED (as specific implementations of the method)

Verification status: ✅ VERIFIED

• Website: GITHUB REPO
• Documentation: PAPER / README
• Source: OPEN
• Development: RESEARCH CODE (Niche)
• Applications: Dual Fermion Method