Purpose of Module

The flook library is a simplifiled API for communicating between fortran code and the Lua scripting language. A basic method is to use flook as an interactive interpreter to pass variables back and forth between a parent fortran program. It does not only serve as a simple input engine but also allows calling specific fortran functions from within Lua. Thus by exposing fortran module procedures one can control the flow of programs as well as parameters in programs.


The library is currently enabled in Siesta and ESL-demo where it can be used to change convergence parameters on the fly and/or being used as an MD back-end. Since it allows exchange of data between Lua and fortran basically every variable in fortran can be exposed to the user via a Lua script.

Background Information

The flook library is built on two libraries; 1) Lua and 2) AOTUS. Both are shipped together with the software and are required when building. Lua is required to be able to run the Lua interpreter in-memory while the AOTUS library is required for the low-level communication layer.


The source code of the flook module is hosted on Github and can be obtained using git or via the release page of flook:

git clone https://github.com/ElectronicStructureLibrary/flook
cd flook
git submodule update --init --recursive

The source code of the flook module itself is contained in the src subdirectory. Lua depends on the readline library (with headers) to be installed. Please install this library first.


The information contained in the Downloading and installation section are likely to work with the latest version of the source code from the repository.

  1. Create an obj directory.

  2. Create a Makefile in the obj directory containing:

    TOP_DIR=.. include ../Makefile

  3. Type make to compile flook, alternatively type make liball to create a unified library (with Lua, AOTUS and flook linked together).


The src/test directory contains a number of small programs that make use of flook. These may be useful to understand the flow of programming. You can build and test flook with the included shell script quick_test.sh.

Source Code

The source code is available from the `flook repo on Github <https://github.com/ElectronicStructureLibrary/flook>`_.