Periodic GFN1-xTB Tight Binding: A Generalized Ewald Partitioning Scheme for the Klopman–Ohno Function
Abstract
A novel formulation is presented for the treatment of electrostatics in the periodic GFN1-xTB tight-binding model. Periodic GFN1-xTB is hindered by the functional form of the second-order electrostatics, which only recovers Coulombic behavior at large interatomic distances and lacks a closed-form solution for its Fourier transform. We address this by introducing a binomial expansion of the Klopman-Ohno function to partition short- and long-range interactions, enabling the use of a generalized Ewald summation for the solution of the electrostatic energy. This approach is general and is applicable to any damped potential of the form |Rn + c|-m. Benchmarks on the X23 molecular crystal dataset and a range of prototypical bulk semiconductors demonstrate that this systematic treatment of the electrostatics eliminates unphysical behavior in the equation of state curves. In the bulk systems studied, we observe a mean absolute error in total energy of 35 meV/atom, comparable to the machine-learned universal force field, M3GNet, and sufficiently precise for structure relaxation. These results highlight the promising potential of GFN1-xTB as a universal tight-binding parametrization.
Copyright and License
© 2025 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0.
Acknowledgement
The authors thank Neil Allan and Thomas Miller for insightful converations, and the developers of both DFTB+ and TBLite for their robust, open-source packages. A.B. thanks Miguel Marques for dicussions on universal force fields, and Nicolas Tancogne-Dejean for reading an early draft of the manuscript.
Funding
This material is based upon work supported by the U.K. EPSRC grant EP/P022308/1, and the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0019390. Open access funded by Max Planck Society.
Contributions
A.B., R.L., and E.D. contributed equally to this work. A.B implemented the periodic GFN1-xTB model, derived the expansion of the KO γ-potential in terms of the binomial theorem, wrote the python workflows for performing and processing calculations, and performed the calculations. R.L implemented the periodic GFN1-xTB model, derived the k = 0 term for S3, derived the gradient theory and implemented the forces, and performed the QCore calculations. J.E.D resolved several blocking issues in the periodic GFN1-xTB implementation, and performed DFT MOF calculations. S.M.M. performed MOF calculations with QCore. P.J.B. supervised and contributed to both the molecular and periodic implementations of the GFN1-xTB model. F.R.M. conceived and supervised the project. All authors discussed the results of the manuscript before submission.
Supplemental Material
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Materials Project IDs, calculation settings and EOS plots for all systems studied, as well as additional details on the asymptotic expansion of the hypergeometric function, and a full derivation of the gradient theory for periodic GFN1-xTB (PDF)
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Additional details
- Engineering and Physical Sciences Research Council
- EP/P022308/1
- Office of Basic Energy Sciences
- DE-SC0019390
- Available
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2025-02-05Published online
- Caltech groups
- Division of Chemistry and Chemical Engineering (CCE)
- Publication Status
- Published