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xTB

xTB

This is the webpage for containing everything to do with xTB.

xTB is a lightweight semi-emperical QM/MM calculator from xTB. It is the calculator that CREST uses.

xTB Documentation

The xTB Documentation is really informative and descriptive. I would recommend you take a look at it. Good examples on how xTB and CREST operate are on the Grimme-Lab Workshops webpage linked below.

How to Install xTB using conda

  • If you are on Windows and have Anaconda/miniconda installed, go to search bar, look for "Anaconda Prompt" and open it. We can run xTB locally in this terminal.

  • If you are on Mac or Linux and you have conda/miniconda installed, open the terminal. We can run xTB locally in this terminal.

If you need to install conda, read my install conda tutorial Here.

For all operating systems, run the commands below. This command creates a new conda environment named xtb with xTB downloaded in it. To activate the conda environment and load xTB you type conda activate xtb.

conda create -n xtb conda-forge::xtb

To know if you xtb is loaded. You should see (xtb) on the left of the terminal prompt line, such as the example below.

(xtb) jeremy@CPU-NAME:~$

How to Run xTB

All you need is the xTB environment loaded and an .xyz file. It is perfectly ok to run xTB in the local terminal. 

xtb initial_geom.xyz --opt tight > xtb.out

You may also call the executable in Jeremy's directory which bypasses having to install xtb yourself by using this command on the HPC.

/home/jerschro/conda/envs/xtb/bin/xtb initial_geom.xyz --opt tight > xtb.out

Looking at the Output Files xTB Generates

The list below is what files CREST generates for a conformational sampling. Important files are listed below and the rest are in the table:

  • xtb_opt.xyz - the optimized structure of the xTB calculation.
  • xtb.out - the terminal output of CREST. The total energy xTB calculates is located in this file.