Potential

eOn supports a large number of potentials, some vendored within the executable and libraries and others via interfaces.

Note

Some of these require compile-time flags, detailed in the installation instructions. The conda-forge package (conda install -c conda-forge eon) ships with Metatomic, XTB, EXT_POT, and the vendored potentials. LAMMPS, ASE, VASP, AMS, and MPI potentials require building from source with the corresponding -Dwith_* flags.

Supported Potentials

External

VASP [POT_KFurthmuller96]

Vienna Ab-Initio Simulation Program (VASP) I/O interface. source build

LAMMPS [POT_Pli95, POT_TAB+22]

Library interface, detailed documentation here. source build

EXT_POT

File-based interface to any external calculator. Detailed documentation here. conda-forge

Added in version 2.0:

AMS(-IO)

Amsterdam modeling suite [POT_teVeldeBB+01], both I/O and library. source build ASE_ORCA

Atomic simulation environment [POT_LMB+17] interface to ORCA [POT_NWBR20]. source build ASE_NWChem

Atomic simulation environment [POT_LMB+17] interface to NWChem [POT_ApraBDJ+20]. source build XTB

Extended Tight binding models via native Fortran-C interfce [POT_BCE+21]. conda-forge Metatomic

Common interface to atomistic machine learning models. conda-forge SocketNWChem

Socket oriented communicator for efficient integration with NWChem [POT_ApraBDJ+20]. conda-forge

Vendored

CuH2

Copper Hydride system

FeHe

Iron-hydrides

EAM_Al

Embedded atom method parameterized for Aluminum.

EMT

Effective medium theory, for metals.

LJ [POT_Jon24]

Lennard-Jones in reduced units, served by rgpot. Neighbor pairs via vesin; timed by ASV TimeMinimizationLJCluster (ljcluster).

LJCluster [POT_Jon24]

Lennard-Jones cluster variant, served by rgpot.

Morse_Pt

Hard sphere morse potential for Platinum, served by rgpot. Neighbor pairs via vesin; timed by ASV TimePointMorsePt / saddle / NEB Morse fixtures.

ZBL

Ziegler-Biersack-Littmark screened nuclear repulsion, served by rgpot.

Lenosky_Si [POT_LSA+00]

Lenosky potential, for silicon.

SW_SI [POT_SW85]

Stillinger-Weber potential, for silicon.

Tersoff_SI [POT_Ter88]

Tersoff pair potential with angular terms, for silicon.

EDIP [POT_JBK+98]

Environment-Dependent Interatomic Potential, for carbon.

TIP4P [POT_JCM+83]

Point charge model for water, also for water-hydrogen and water on platinum.

SPCE [POT_BGS87]

Extended simple point charge model for water

Configuration

[Potential]

Potential configurations

Several potentials have additional configuration stanzas.

Metatomic

XTB

ZBL

NWChem

Support for nwchem works best with the socket potential structure as noted in the reproduction details of the Optimal transport Gaussian Process [POT_GJonsson25], and can lead to manyfold increases in speed compared to file or ASE interfaces [POT_Gos25].

Warning

NWChem’s Fortran i-PI socket driver truncates UNIX socket names to approximately 30 characters. The full socket path is /tmp/ipi_<unix_socket_path>, so unix_socket_path should be kept short (under ~20 characters). For example, eon_nwchem works but eon_nwchem_test_socket will be silently truncated, causing a connection failure with no clear error message.

An older ASE interface exists as well.

ASE potentials

There are several specific ASE potentials supported,

AMS potentials

Both a direct server model and a file based integration exist.

Along with helpers to set environment variables for these calculations.

References

[POT_ApraBDJ+20] (1,2)

E. Aprà, E. J. Bylaska, W. A. De Jong, N. Govind, K. Kowalski, T. P. Straatsma, M. Valiev, H. J. J. Van Dam, Y. Alexeev, J. Anchell, V. Anisimov, F. W. Aquino, R. Atta-Fynn, J. Autschbach, N. P. Bauman, J. C. Becca, D. E. Bernholdt, K. Bhaskaran-Nair, S. Bogatko, P. Borowski, J. Boschen, J. Brabec, A. Bruner, E. Cauët, Y. Chen, G. N. Chuev, C. J. Cramer, J. Daily, M. J. O. Deegan, T. H. Dunning, M. Dupuis, K. G. Dyall, G. I. Fann, S. A. Fischer, A. Fonari, H. Früchtl, L. Gagliardi, J. Garza, N. Gawande, S. Ghosh, K. Glaesemann, A. W. Götz, J. Hammond, V. Helms, E. D. Hermes, K. Hirao, S. Hirata, M. Jacquelin, L. Jensen, B. G. Johnson, H. Jónsson, R. A. Kendall, M. Klemm, R. Kobayashi, V. Konkov, S. Krishnamoorthy, M. Krishnan, Z. Lin, R. D. Lins, R. J. Littlefield, A. J. Logsdail, K. Lopata, W. Ma, A. V. Marenich, J. Martin Del Campo, D. Mejia-Rodriguez, J. E. Moore, J. M. Mullin, T. Nakajima, D. R. Nascimento, J. A. Nichols, P. J. Nichols, J. Nieplocha, A. Otero-de-la-Roza, B. Palmer, A. Panyala, T. Pirojsirikul, B. Peng, R. Peverati, J. Pittner, L. Pollack, R. M. Richard, P. Sadayappan, G. C. Schatz, W. A. Shelton, D. W. Silverstein, D. M. A. Smith, T. A. Soares, D. Song, M. Swart, H. L. Taylor, G. S. Thomas, V. Tipparaju, D. G. Truhlar, K. Tsemekhman, T. Van Voorhis, Á. Vázquez-Mayagoitia, P. Verma, O. Villa, A. Vishnu, K. D. Vogiatzis, D. Wang, J. H. Weare, M. J. Williamson, T. L. Windus, K. Woliński, A. T. Wong, Q. Wu, C. Yang, Q. Yu, M. Zacharias, Z. Zhang, Y. Zhao, and R. J. Harrison. NWChem: past, present, and future. Journal of Chemical Physics, 152(18):184102, May 2020. doi:10.1063/5.0004997.

[POT_BCE+21]

Christoph Bannwarth, Eike Caldeweyher, Sebastian Ehlert, Andreas Hansen, Philipp Pracht, Jakob Seibert, Sebastian Spicher, and Stefan Grimme. Extended tight-binding quantum chemistry methods. WIREs Computational Molecular Science, 11(2):e1493, 2021. doi:10.1002/wcms.1493.

[POT_BGS87]

H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma. The missing term in effective pair potentials. The Journal of Physical Chemistry, 91(24):6269–6271, November 1987. doi:10.1021/j100308a038.

[POT_Gos25]

Rohit Goswami. Efficient exploration of chemical kinetics. October 2025. arXiv:2510.21368, doi:10.48550/arXiv.2510.21368.

[POT_GJonsson25]

Rohit Goswami and Hannes Jónsson. Adaptive Pruning for Increased Robustness and Reduced Computational Overhead in Gaussian Process Accelerated Saddle Point Searches. ChemPhysChem, November 2025. doi:10.1002/cphc.202500730.

[POT_Jon24] (1,2)

Lennard Jones. On the determination of molecular fields. —II. From the equation of state of a gas. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 106(738):463–477, October 1924. doi:10.1098/rspa.1924.0082.

[POT_JCM+83]

William L. Jorgensen, Jayaraman Chandrasekhar, Jeffry D. Madura, Roger W. Impey, and Michael L. Klein. Comparison of simple potential functions for simulating liquid water. The Journal of Chemical Physics, 79(2):926–935, July 1983. doi:10.1063/1.445869.

[POT_JBK+98]

João F. Justo, Martin Z. Bazant, Efthimios Kaxiras, V. V. Bulatov, and Sidney Yip. Interatomic potential for silicon defects and disordered phases. Physical Review B, 58(5):2539–2550, August 1998. doi:10.1103/PhysRevB.58.2539.

[POT_KFurthmuller96]

G. Kresse and J. Furthmüller. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Physical Review B, 54(16):11169–11186, October 1996. doi:10.1103/PhysRevB.54.11169.

[POT_LMB+17] (1,2)

Ask Hjorth Larsen, Jens Jørgen Mortensen, Jakob Blomqvist, Ivano E. Castelli, Rune Christensen, Marcin Du\lak, Jesper Friis, Michael N. Groves, Bjørk Hammer, Cory Hargus, Eric D. Hermes, Paul C. Jennings, Peter Bjerre Jensen, James Kermode, John R. Kitchin, Esben Leonhard Kolsbjerg, Joseph Kubal, Kristen Kaasbjerg, Steen Lysgaard, Jón Bergmann Maronsson, Tristan Maxson, Thomas Olsen, Lars Pastewka, Andrew Peterson, Carsten Rostgaard, Jakob Schiøtz, Ole Schütt, Mikkel Strange, Kristian S. Thygesen, Tejs Vegge, Lasse Vilhelmsen, Michael Walter, Zhenhua Zeng, and Karsten W. Jacobsen. The atomic simulation environment—a Python library for working with atoms. Journal of Physics: Condensed Matter, 29(27):273002, June 2017. doi:10.1088/1361-648X/aa680e.

[POT_LSA+00]

Thomas J Lenosky, Babak Sadigh, Eduardo Alonso, Vasily V Bulatov, Tomas Diaz De La Rubia, Jeongnim Kim, Arthur F Voter, and Joel D Kress. Highly optimized empirical potential model of silicon. Modelling and Simulation in Materials Science and Engineering, 8(6):825–841, November 2000. doi:10.1088/0965-0393/8/6/305.

[POT_NWBR20]

Frank Neese, Frank Wennmohs, Ute Becker, and Christoph Riplinger. The ORCA quantum chemistry program package. The Journal of Chemical Physics, 152(22):224108, June 2020. doi:10.1063/5.0004608.

[POT_Pli95]

Steve Plimpton. Fast Parallel Algorithms for Short-Range Molecular Dynamics. Journal of Computational Physics, 117(1):1–19, March 1995. doi:10.1006/jcph.1995.1039.

[POT_SW85]

Frank H. Stillinger and Thomas A. Weber. Computer simulation of local order in condensed phases of silicon. Physical Review B, 31(8):5262–5271, April 1985. doi:10.1103/PhysRevB.31.5262.

[POT_Ter88]

J. Tersoff. Empirical interatomic potential for silicon with improved elastic properties. Physical Review B, 38(14):9902–9905, November 1988. doi:10.1103/PhysRevB.38.9902.

[POT_TAB+22]

Aidan P. Thompson, H. Metin Aktulga, Richard Berger, Dan S. Bolintineanu, W. Michael Brown, Paul S. Crozier, Pieter J. In 'T Veld, Axel Kohlmeyer, Stan G. Moore, Trung Dac Nguyen, Ray Shan, Mark J. Stevens, Julien Tranchida, Christian Trott, and Steven J. Plimpton. LAMMPS - a flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales. Computer Physics Communications, 271:108171, February 2022. doi:10.1016/j.cpc.2021.108171.

[POT_teVeldeBB+01]

G. te Velde, F. M. Bickelhaupt, E. J. Baerends, C. Fonseca Guerra, S. J. A. van Gisbergen, J. G. Snijders, and T. Ziegler. Chemistry with ADF. Journal of Computational Chemistry, 22(9):931–967, 2001. doi:10.1002/jcc.1056.