This part of the documentation only contains information which is relevant if you are planning to modify or extend the source code of the SpinParser applications. The SpinParser application, without modification, is already suited to solve a broad class of spin models on customizable lattice geometries.

The user manual, as well as installation instructions, can be found on the project's Github page.

The user manual for the optional Python tools, which are included in the SpinParser software, can be found here.

Potential reasons to modify the source code could include:

implementation of custom, specialized flow equations
implementation of additional measurements or observables
implementation of addidional information / log output
Change of the numerical internal integration routines
Change of the numerical differential equation solver
Use of some algorithms / libraries in other projects

Since the SpinParser project aims to make pseudofermion functional renormalization group (pf-FRG) calculations available to a broader community without the need to write additional code, no large-scale developer guide for the application and its libraries exists. However, on the code level, functions and class interfaces are well documented and a minimal amount of context is provided in class definitions.

For a general understanding of the code, a good starting point for reading are the SpinParser, FrgCore, and EffectiveAction classes. The latter two are abstract definitions, which the SpinParser interfaces when solving pf-FRG flow equations; concrete implementations exist e.g. as SU2FrgCore and SU2EffectiveAction. The concrete implementations of the EffectiveAction implement e.g. symmetries in the arguments of vertex functions. Measurements are performed by interfacing with the Measurement class.

The classes Lattice, FrequencyDiscretization, and CutoffDiscretization define the mathematical spaces on which the flow equations are solved. At the beginning of the simulation, based on the user-provided lattice spin model, a Lattice object is generated by the LatticeModelFactory.

Dynamic load balancing is performed by the LoadManager library, which can be flexibly applied also to new flow equation implementations.