# Readme sfcf.jl

This is a framework to compute Schrödinger functional correlation functions based on LatticeGPU (https://igit.ific.uv.es/alramos/latticegpu.jl).

## Requirements

The required packages are listed below

- LatticeGPU
- CUDA
- TOML
- TimerOutputs
- ArgParse
- InteractiveUtils
- BDIO
- MD5

The versions are resolved with the enviroment in the main sfcf.jl directory. The recomended version of julia is julia 1.8.5.

## Input file

A template for the input file can be found at input/sfcf.in.

* [Space]

 - size : Lattice size. The last component is the time extent.
 - blocks : Sub-lattices parallelization on the GPU. Each sub-lattice length must divide each lattice length.
 - phi0 : Phases defining the field at the boundary t = 0.
 - phiT : Phases defining the field at the boundary t = T. 
 - cG : Boundary improvement coefficient for the gauge field.
 
* [Fermion]

 - beta : Bare coupling. 
 - kappa : Value of the hopping parameter.
 - theta : Phase for the fermion field in the spatial directions.
 - csw : Sheikholeslami-Wohlert coefficient
 - ct : Boundary improvement coefficient for the fermion field.

* [Solver]

 - tolerance : Stopping criteria for the solver. The residue of the solver is meassured as the normalized residue for a source given by gamma_5 * D_w * gamma_5 * B , where B is the boundary source for each spin/color.
 - maxiter : Maximum number of iterations for the solver.

## Configuration input

Current allowed input formats for the configuration are:

 - Native LatticeGPU (default) : Native io format from LatticeGPU
 - cern format : Read the format output given the function export_cnfg_cern() in sfqcd (https://gitlab.ift.uam-csic.es/alberto/sfqcd). This is specified with the option --cern

## Execution command

The available options are:

 * -c (needed) : Specifies the gauge configuration.
 * -i (needed) : Specifies the input file.
 * --cern : Read the gauge config with cern format

An example of an execution command is

   $ julia1.8 sfcf.jl -i ./input/sfcf.in -c ./cnfg/randfield 

note that the main program sfcf.jl assumes that ./ is the main sfcf.jl directory to activate the enviroment.

## Output

The main program outputs two files. the name is given by the input file [Run] [name]:

 * name.log : Log file with differ/ent information about the run

 * name.bdio : BDIO file with the correlation functions. The BDIO.jl package can be found at https://gitlab.ift.uam-csic.es/alberto/bdio.jl . The structure is the following
 
    - Record 1 : Information about the parameters

    - Record 14 : Format ihdr check

    - Record 8 : Gauge config name and MD5 saved as String. Results for the correlation functions, saved in the following order: f_P, f_A, f_1, g_P, g_A, k_V, l_V, k_1, k_T, l_T. All of them are saved as Complex{Float64}

Note that if the BDIO file exists, the results will be appended in Record 8.