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Build Status	License

Determinant quantum Monte Carlo (DQMC) code for simulating a quantum critical metal, a Fermi sea coupled to antiferromagnetic bosonic fluctuations, in two spatial dimensions.

A version of this code has been used to produce (most of) the results in the following paper:

Hierarchy of energy scales in an O(3) symmetric antiferromagnetic quantum critical metal: a Monte Carlo study
Carsten Bauer, Yoni Schattner, Simon Trebst, Erez Berg

Performance comparison

The figure below shows a comparison of three different DQMC codes written in C++, Fortran, and Julia. Specifically, it shows the time it takes to perform one sweep of local updates in space and imaginary time for a spin-fermion model (studied in the paper linked above). All kinds of special features, such as a small magnetic flux to improve finite size effects, are turned off.

Codes:

• C++ code by Max Gerlach (repository, used in this paper).
• Private Fortran code by Yoni Schattner (used in this paper).
• Julia DQMC implementation in this repository.

Settings

Environmental variables:

• LATTICES: folder with ALPS XML lattice files (mandatory unless you're me)
• WALLTIME: Set a walltime limit for the algorithm. (optional)
• JULIA_DQMC: path to the root of this repo (optional, currently only used in live.jl/ipynb and test_live.ipynb to activate the environment)

Modes

Special modes as indicated by fields in dqmc.in.xml:

• EDRUN: if set to true, temporal gradients and quartic term in bosonic action are turned off.
• TIMING: stop after thermalization phase and report speed and allocations of all major functions.