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 task 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 commandline and the default settings followed by a trouble shooting 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 scences.

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 webinterface)

  • 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 a xtb interface

  • CP2K has an GFN1-xTB implementation since version 7.1

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