User Guide to Semiempirical Tight Binding

This user guide focuses on the semiempirical quantum mechanical methods GFNn-xTB, their descendants, and corresponding composite schemes as implemented in the xtb (extended tight binding) program package.

We provide a number of detailed guides dealing with common tasks that can be performed easily with the xtb program. All guides are usually structured the same way, starting with some simple examples using only the command line and the default settings, followed by a troubleshooting section. Detailed inputs are provided in a ready-to-use fashion to solve some more special but still common tasks with xtb together with some insights into the theory used behind the scenes.

Recent developments, news, and publications

  • 2024-07-23: xtb version 6.7.1 released by Albert Katbashev

    We are happy to release a bugfix version of xtb. Please note that due to the deprecation of the currently used MSVC C++ compiler, the Windows version is 6.7.1pre. The compilation excluded C-API tests for xtb and CPCM-X and used the previous version of dftd4 (v3.4.0). In the next release, we will likely fully switch to the icx-cl compiler.

    Many thanks to Sebastian Ehlert (@awvwgk), Igor S. Gerasimov (@foxtran), and Thomas Rose (@Thomas3R) for contributing to this release. Special thanks to Marcel Stahn (@MtoLStoN), who made the compilation of the Windows version possible.

    xtb logo

  • 2024-03-04: xtb version 6.7.0 released by Albert Katbashev

    We are happy to release a new version of xtb. This version introduced several powerful features and enhancements, including the new CPCM-X solvation model, support for periodic boundary conditions in GFN-FF, and an implementation of dipole moments within the GFN-FF framework. A range of computational methods was added or refined, such as the Dimer Projection (DIPRO) method, PTB (Density Tight-Binding) potential, and support for Raman activity calculations with user-defined wavelength and temperature. External-driver optimization was improved through automatic writing of updated coordinate files and better output formatting. Users also gained access to new features like the sandwich potential model, total-atom constraints, and COSMO file output in TM convention.

    Many thanks to Benedict Bädorf (@benbaed), Sebastian Ehlert (@awvwgk), Joel Einbinder (@JoelEinbinder), Julia Kohn (@demonic-daisy), Marcel Müller (@marcelmbn), Christoph Plett (@cplett), Thomas Rose (@Thomas3R), Marcel Stahn (@MtoLStoN), and Jinzha Zeng (@njzjz) for contributing to this release.

    xtb logo

  • 2022-05-15: xtb version 6.5.0 released by Sebastian Ehlert

    We are happy to release a new version of xtb with exciting new features. First of all, we improved the user-friendliness of the error messages in the geometry reader by adopting our IO-library, which is already in wide use in dftd4, gcp and other projects. No more invalid input provided obscure error messages, but actual pointers on what went wrong with the input.

    We also improved the capability of existing geometry readers to keep up to date with the parent programs, for example we now support the $eht charge=0 unpaired=0 line to set the system charge and number of unpaired electrons, which was added in a Turbomole 7.5. Furthermore, we are happy to have now support for QChem molecule files (.qchem), FHI-aims geometry inputs (geometry.in) and QCSchema formatted JSON (.json).

    xtb logo

  • 2021-12-13: DFTB+ version 21.2 released by Sebastian Ehlert

    A new version of DFTB+ is now available with support for the xTB methods. Due to the integration in DFTB+ most of the features available for the DFTB Hamiltonian can be readily used with the xTB Hamiltonians as well, including periodic calculations with k-point sampling, geometry optimizations, molecular dynamics and frequency calculations. Both GFN1-xTB and GFN2-xTB are available for the DFTB+ version 21.2 at the moment.

    Furthermore, we integrated parts the battle-proven rational function optimizer from xtb --opt into DFTB+ to allow fast and robust geometry optimizations both for molecular and periodic systems. Preliminary tests show an order of magnitude improvements in the convergence compared with the previous default (c.f. dftbplus#862).

  • 2021-08-27: QCxMS version 5.1.2 released by Jeroen Koopman

    This new update of the QCxMS program is linked against the AVX2 processor extension for increased performance. CID and EI runmode changes and bugfixes are implemented. The local run-script pqcxms was re-written and now performs better for parallel calculations.

    For a detailed description of all changes, check out the GitHub repository.

    QCxMS logo

See the news archive for all posts.

xTB in Other Quantum Chemistry Programs

The xTB-methods are now officially available in other quantum chemistry programs!

  • in Orca 4.2 an IO-based interface to the xtb binary is available

  • AMS 2019 implements GFN1-xTB in their DFTB module

  • the entos program implements GFN1-xTB (also available in the web interface)

  • the computational chemistry framework cuby4 supports xtb

  • Turbomole does support GFN1-xTB and GFN2-xTB since version 7.4

  • QCEngine supports calculations with the xtb API

  • the GMIN, OPTIM, and PATHSAMPLE global optimization tools provide an xtb interface

  • CP2K has a GFN1-xTB implementation since version 7.1

  • DFTB+ support GFN1-xTB and GFN2-xTB since version 21.2

We missed your project here? No problem, just give us a hint at the mailing list or open an issue at GitHub.

Quickstart

Guides

Submodules

CREST

ENSO

CENSO

QCxMS

QCxMS2

Misc