GFN0-xTB

This repository contains a standalone implementation of the GFN0-xTB method (https://doi.org/10.26434/chemrxiv.8326202.v1), adapted from the xtb code.

The default CMake and meson builds compile a statically linked library (libgfn0.a) that can be linked in other projects.

main.f90 in testprog/ demonstrates the in-code usage.

Building the Project

Make sure you have the following dependencies installed:

CMake and make, or meson and ninja build systems
Fortran and C compilers (e.g., gfortran/gcc or ifort/icc)

Instructions

Follow these steps to build the project:

Create a build directory and navigate to it
```
mkdir _build
cd _build
```
Export the compilers (here for example ifort/icc) and depending on your chosen build system set up the build:
- generate the build files using CMake:
```
FC=ifort CC=icc cmake ..
```
- generate the build files using meson:
```
FC=ifort CC=icc meson ..
```
I you wish to build the test-binary, add -Dbuild_exe=true to either the cmake or meson setup command.
Depending on your chosen build system, build the project. If you have multiple cores/processors, you can speed up the build process by specifying the number of cores to use with the -j option. For example, to use 4 cores:
- With CMake/make:
```
make -j4
```
- With meson/ninja:
```
ninja -j4
```

Cleaning the Build

To clean the build files, simply delete the build directory:

rm -rf _build