Potential Models
The following potentials are currently available in GULP:
- Two-body:
-
- Buckingham
- Buckingham four range
- Lennard-Jones (either in A and B or epsilon and sigma form)
- Morse (with and without coulomb offset)
- Harmonic (with and without coulomb offset)
- Spring (for core-shell interactions)
- Coulomb (pure coulomb offset)
- General (Aexp(-r/rho)/r**m -C/r**n)
- Splined potentials (rational function or cubic)
- Covalent-exponential
- Rydberg
- Inverse Gaussian
- Coulomb x erfc
- Stillinger-Weber two-body with cutoff smoothing
- Breathing shell potential (harmonic)
- Breathing shell potential (exponential)
- Qtaper
- Fermi-Dirac
- Squared harmonic
- Tsuneyuki
- Charge over distance squared
- Mei-Davenport two body
- Repulsive erfc
- Short-range glue
- Force constant model
- Three-body:
-
- Three-body harmonic (with or without exponential decay)
- Axilrod-Teller three-body potential
- Exponentially decaying three-body term
- Stillinger-Weber three-body with cutoff smoothing
- Urey-Bradley three-body potential
- Murrell-Mottram potential
- Bond-bond cross term three-body potential
- Cosine harmonic
- Bond-angle cross term
- Linear-threebody
- Hydrogen bond potential
- Equatorial
- UFF3
- Four-body:
-
- Four-body torsional (standard and Ryckaert-Bellemans)
- ESFF torsional
- UFF4
- Inversion potential
- Angle-angle cross potential
- UFF out of plane
- Six-body:
-
- Cross out of plan
- Many-body:
-
- Embedded Atom Method - Sutton-Chen and other forms
- Tersoff potential
- REBO model of Brenner and co-workers (2003 version)
- ReaxFF model of van Duin and co-workers
- EDIP model for carbon of Nigel Marks
Other points to note relating to potential models in GULP:
- multiple potentials can act over the same range
- C6 terms can be converged using lattice summation methods
- the cell multipole method can be used for cluster electrostatics
- combination rules are available for Lennard-Jones parameters
- molecules can be automatically created and optionally Coulomb subtracted
- potentials can inter- or intra-molecular or molecular mechanics
- potentials can be tapered smoothly to zero
In addition to the potentials that are built into GULP, it is also possible to use other models via compilation with OpenKIM which is a cyberinfrastructure for improving the reliability of molecular and multiscale simulations of materials. It includes a repository of interatomic potentials that are exhaustively tested, tools to help select among existing potentials and develop new ones, and standard integration methods for using potentials in major simulation codes.
