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Semiempirical Extended Tight-Binding Program Package

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This is the offical repository of the xtb program package developed by the Grimme group in Bonn.

Extended Tight Binding


Build Status

Statically linked binaries (Intel Compiler) can be found at the latest release page, a version for Linux (Intel 18.0.2, GLIBC 2.19) and Windows (Intel 2022) is provided. The xtb program and library are packaged on conda-forge for Linux (x86_64, aarch64, ppc64le) and MacOS (x86_64, arm64). For homebrew users a custom tap is available at grimme-lab/homebrew-qc providing prebuilt MacOS/x86_64 binaries, for MacOS/arm64 binaries will be compiled on installation automatically.

Bleeding edge releases (Linux only) of the latest source from this repository are available on the continuous release tag.

This projects supports two build systems, meson and CMake. A short guide on the usage of each is given here, follow the linked instructions for a more detailed information (meson guide, CMake guide).


Using meson as build system requires you to install a fairly new version like 0.51 or newer. To use the default backend of meson you have to install ninja version 1.7 or newer.

export FC=ifort CC=icc
meson setup build --buildtype release --optimization 2
ninja -C build test

Make sure the testsuite is running without errors.

To install the xtb binaries to /usr/local use (might require sudo)

ninja -C build install

For more information on the build with meson see the instructions here.


The CMake build system requires both make and CMake to be installed, the latter has to be version 3.9 or newer.

Building xtb with CMake works with the following chain of commands:

cmake -B build -DCMAKE_BUILD_TYPE=Release
make -C build
make -C build test

To install the xtb binaries to /usr/local use (might require sudo)

make -C build install

For more detailed information on the build with CMake see the instructions here.


Conda Version

Installing xtb from the conda-forge channel can be achieved by adding conda-forge to your channels with:

conda config --add channels conda-forge

Once the conda-forge channel has been enabled, xtb can be installed with:

conda install xtb

It is possible to list all of the versions of xtb available on your platform with:

conda search xtb --channel conda-forge


Documentation Status

The xtb documentation is hosted at read-the-docs.


Please read our contributing guidelines before contributing to this project.


We are developing this program to make our research possible. Many of the features that xtb has today have been added because there was a dire need for them and we had many contributors who made these features reality:

Contributors are listed in alphabetical order. Some contributions predate the GitHub release of this project and are not visible in the repository commit history. For the contributor data from the commit history since then look here.


General Reference to xtb and the implemented GFN methods:

  • C. Bannwarth, E. Caldeweyher, S. Ehlert, A. Hansen, P. Pracht, J. Seibert, S. Spicher, S. Grimme WIREs Comput. Mol. Sci., 2020, 11, e01493. DOI: 10.1002/wcms.1493

for GFN-xTB:

for GFN-FF:

for GBSA and ALPB implicit solvation:

  • S. Ehlert, M. Stahn, S. Spicher, S. Grimme, J. Chem. Theory Comput., 2021, 17, 4250-4261 DOI: 10.1021/acs.jctc.1c00471

for DFT-D4:

  • E. Caldeweyher, C. Bannwarth and S. Grimme, J. Chem. Phys., 2017, 147, 034112. DOI: 10.1063/1.4993215
  • E. Caldeweyher, S. Ehlert, A. Hansen, H. Neugebauer, S. Spicher, C. Bannwarth and S. Grimme, J. Chem. Phys., 2019, 150, 154122. DOI: 10.1063/1.5090222
  • E. Caldeweyher, J.-M. Mewes, S. Ehlert and S. Grimme, Phys. Chem. Chem. Phys., 2020, 22, 8499-8512. DOI: 10.1039/D0CP00502A

for sTDA-xTB:

  • S. Grimme and C. Bannwarth, J. Chem. Phys., 2016, 145, 054103. DOI: 10.1063/1.4959605

in the mass-spec context:

for metadynamics refer to:

for SPH calculations refer to:

All references are available in bibtex format.


xtb is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

xtb is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the GNU Lesser General Public License for more details.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in xtb by you, as defined in the GNU Lesser General Public license, shall be licensed as above, without any additional terms or conditions.