Installation

General Considerations

Similar to xtb, the crest software is open-source and available under the LGPL 3.0 license on GitHub. The guideline for installation is also similar to xtb.

Warning: Primary operating system (OS) for the development and application of crest is Linux. While it is possible to install crest on Windows and macOS, support for these platforms may be more limited.

Straighforward Installation

The most straightforward way to install crest is by downloading the precompiled binaries. Here, you can also get a bleeding-edge version of the program. After downloading the appropriate version, extract it, make it executable, and add it to your PATH variable:

To verify that the executable is correctly linked, use:

which crest

And check the installed version with:

crest --version

Tip: You can add the full path to your Bash shell configuration file (~/.bashrc) to automatically load crest in new sessions.

For crest to work properly, xtb is required. crest will automaticall use the xtb program sourced, but with the keyword --xnam <Path to xtb> you can define the xtb binary that will be used by crest.

Homebrew Support

crest can also be installed with Homebrew. The support is provided by an additional GitHub repository that provides access also to additional software. crest can be installed on MacOS via

brew tap grimme-lab/qc
brew install crest

Tip: The latest version available via Homebrew is CREST 2.1.2, but CREST 3 will be available soon. For this workshop, also crest 2.1.2 can be used.

Compilation

A more advanced approach is to compile crest from the source code. Native compilation has certain advantages over precompiled binaries, such as producing a system-tailored binary and allowing modifications to the software in place.

Here, we follow a minimalistic build using our default toolchain: the meson build system and the ifort/icc compilers.

First step is to clone the official GitHub repository via:

git clone https://github.com/crest-lab/crest.git

Then, define the Fortran and C compilers, which can be installed via Intel’s Developer Toolkit:

export FC=ifort CC=icc

Finally, you can build the project with Meson:

meson setup _build --prefix=$PWD/_dist
meson install -C _build

Alternatively, gfortran/gcc compilers are also supported. For a complete list of supported compilers and backends, please see the github page.