Step-by-step Installation

Table of contents

1. Requirements
2. Installation from precompiled binaries
3. Compiling from source

CREST was built as a commandline-based application for UNIX distributions. Therefore, this guide will assume that you are familiar with the basic navigation in the terminal. Installation instructions shown in the following were tested on Ubuntu 20.04 LTS .

Requirements

Requirements for the installation can depend on whether you decide to install CREST from the precompiled binaries, or build the program on yourself locally:

• In general, compiling the program from source will provide you with a binary more tailored to your specific computer/architecture. Furthermore, you will be able to get the newest developments and code updates more quickly. However, building the program from source will require some effort.
• The installation of statically compiled binariesThis means the source code has been translated into ‘machine language’ and should not need any other dependencies at runtime besides the obvious. from GitHub is faster and will in most cases be sufficient. However, in rare cases you might encounter runtime errors. Additionally, the precompiled program is updated only periodically with a new release, so some code updates might not yet be included.

Most CREST applications will require access to the xtb program. You will need to install xtb on your machine and make sure it can be executed globally. You can follow the installation instructions for xtb on the GitHub repository , but note that most of the process is similar to the CREST installation presented here. If you plan on using QCG, you will also need to install the xtbiff program.

Installation from precompiled binaries

Installation via precompiled static binaries is the the simplest option. First, you will have to download the program.

1. Navigate to the Releases tab on CREST’s GitHub page

   

2. Select the release version you want to install (probably the one flagged as “Latest”) and download the packed binary

   

3. Move the packed binary to some place of your choice (e.g., /home/$USER/bin/) and unpack it there

   unzip crest.zip
   

4. Assuming you put CREST in /home/$USER/bin/, make the statically linked binary an executable (might require sudo) with

   chmod +x /home/$USER/bin/crest
   

5. Then export it to your PATH variable to make it accessible on your system, if necessary

   export PATH=$PATH:/home/$USER/bin/
   

   You can check if the export was successful by executing the command

   which crest
   

   which should return the full path to the CREST binary. You can also add the export line to your ~/.bashrc to load it on the terminal startup.

That’s pretty much all. If xtb has been correctly installed, you can now start to use CREST. You can test the installation, for example by executing

crest --version

which should print the program header to the terminal.

Compiling from source

If you wish to build the program yourself from the source code, you will first have to obtain it. For this, navigate to CREST’s GitHub page and either fork it (if you are familiar with GitHub), or locate the “Code” button.

There, you will have the option to either clone the project with git via the command line

git clone https://github.com/crest-lab/crest.git /directory/of/your/choice

or simply download the ZIP file. After you have obtained the source code, you will need to build the program. Instructions on this can be found on the next page.

Continue: Compiling from Source