# Keywords¶

## Summary of all keywords¶

AllowMissingParameters
Type: Bool No When parameters are not found for bonds, angles, dihedrals, or inversions, the first entry in the database will be used.
AntechamberIntegration
Type: Bool No Automatic atom typing EXPERIMENTAL: Use the Antechamber program to automatically determine atom types for the GAFF force field. This may run a geometry optimization with MOPAC under the hood in order to determine the charges (see keyword AntechamberTask), which might not work for very large systems.
AntechamberTask
Type: Multiple Choice GeometryOptimization [GeometryOptimization, SinglePoint] If antechamber is envoked to guess atomtypes and charges (GAFF force field), select the task for charge guessing with MOPAC
APPLE&P
Type: Block Options for the APPLE&P force field.
LongRangeCorrection
Type: Bool Yes Add long-range correction Add a long-range dispersion correction to the energy and pressure for 3D-periodic systems. This correction should be enabled only for a homogeneous liquid.
MuMu14Scaling
Type: Float 1.0 Mu-Mu 3rd-neighbor scaling Scaling factor for dipole-dipole interactions between atoms connected to 3rd order (via a dihedral).
QMu14Scaling
Type: Float 0.8 Q-Mu 3rd-neighbor scaling Scaling factor for charge-dipole interactions between atoms connected to 3rd order (via a dihedral).
QQ14Scaling
Type: Float 0.8 Q-Q 3rd-neighbor scaling Scaling factor for charge-charge interactions between atoms connected to 3rd order (via a dihedral).
RD14Scaling
Type: Float 1.0 RD 3rd-neighbor scaling Scaling factor for repulsion/dispersion interactions between atoms connected to 3rd order (via a dihedral).
BondsUsage
Type: Multiple Choice Auto [Input, None, Guess, Auto] Controls what bonds are used by the engine. The choice auto means: guess in case there are no bonds. Guessing only happens at the first MD step, or first geometry optimization step.
CheckDuplicateRules
Type: Bool Yes The database could contain duplicate entries. For torsions this is a feature, and the potentials will be added. For all other terms this is no allowed, and if detected the program stops. One should fix the database or set the checking to false. As always the last entry will be used.
DipoleConvergenceThreshold
Type: Float 1e-06 a.u. Convergence criterion for induced point dipoles, in atomic units. When the length of every atomic delta_mu vector between two iterations becomes below the tolerance, the procedure is considered converged.
DoChargeCheck
Type: Bool No Check that the sum of atomic (partial) charges equals the total charge of the system.
EnergyTerms
Type: Block expert key, that allows you to disable specific energy terms.
Angle
Type: Bool Yes Whether to use angle (bend) energy.
Coulomb
Type: Bool Yes Whether to use coulomb energy.
Dispersion
Type: Bool Yes Whether to use dispersion energy.
Inversion
Type: Bool Yes Whether to use inversion energy.
Stretch
Type: Bool Yes Whether to use stretch energy.
Torsion
Type: Bool Yes Whether to use torsion energy.
EwaldSummation
Type: Block Configures the details of the particle mesh Ewald (PME) summation of the Coulomb interaction.
Alpha
Type: Float -1.0 1/Angstrom This parameter shifts the workload from real space (smaller alpha) to reciprocal space (larger alpha). Using a larger [Alpha] without decreasing [GridSpacing] may increase the error in the reciprocal-space contribution. Set to zero to disable the reciprocal-space Ewald part. Negative value means the [Alpha] will be determined automatically from the [Tolerance] and [RealSpaceCutoff] values.
Enabled
Type: Bool Yes Set to false to use real-space pair summation instead of the Ewald, which is the default and the only option for molecules, 1D and 2D periodic systems.
GridSpacing
Type: Float 0.5 Angstrom Grid spacing in the particle mesh Ewald method. Smaller grid spacing will make the reciprocal energy calculation more accurate but slower. Using a larger [Alpha] value may require a smaller GridSpacing to be accurate.
RealSpaceCutoff
Type: Float 0.0 Angstrom Set the cutoff value for the real-space summation. Zero means the internal defaults will be used depending on the [Alpha] (if Alpha=0 then the cutoff will be set to 50 Bohr, otherwise to 20 Bohr).
Tolerance
Type: Float 1e-10 Value of the error function that should be used to determine the cutoff radius for real-space Ewald summation if [Alpha] is set on input. Alternatively, if the [RealSpaceCutoff] is set but [Alpha] is not then the [Tolerance] value affects the [Alpha]. Larger values will make the real-space summation faster but less accurate.
ForceFieldFile
Type: String Force field library Path to the force field parameter file
ForceFieldPatchFile
Type: String Force field patch file Path to the force field patch parameter file (additional parameters, missing from main file). Cannot be used when atomtypes are guessed.
GuessCharges
Type: Bool No Use another engine to calculate/guess the charges to be used by the force field.
GuessChargesConfig
Type: Block Guess charges to be used by the forcefield
EngineType
Type: String dftb Engine that can calculate or guess charges
LinearizationEnergyForRepulsion
Type: Float 3.0 Hartree The Lennard-Jones potential becomes extremely repulsive at short distances. The distance is determined where the potential reaches this threshold, for smaller distances a linear expression is used, reducing the repulsion.
LoadCharges
Type: Block Load charges from a file to be used as forcefield charges
File
Type: String Name of the (kf) file
Section
Type: String AMSResults Section name of the kf file
Variable
Type: String Charges variable name of the kf file
NeighborListSkin
Type: Float 2.5 Angstrom Thickness of the buffer region added to the NonBondedCutoff when building a neighbor list.
NonBondedCutoff
Type: Float 15.0 Angstrom Distance beyond which the non-bonded pair interactions (Coulomb and Van der Waals) will be ignored. The interactions are smoothly damped starting from 0.9*NonBondedCutoff. Has no effect on the Coulomb term for periodic systems, as Ewald summation is used.
TaperPairInteractions
Type: Bool Yes Smooth non-bonded pair interactions in the distance range between 90% and 100% of the [NonBondedCutoff] to avoid energy and force jump near the cutoff.
Type
Type: Multiple Choice UFF [UFF, Amber95, GAFF, Tripos5.2, APPLE&P, UserDefined] Type of force field to be used
UFF
Type: Block Option for the UFF force filed.
AtomTypesFile
Type: String mmatomtypes_db Expert option: Select the file that defines how UFF determines the atom types
Database
Type: String general_db Expert option: Select the file that defines the UFF parameters per atom type
ElementsFile
Type: String elements_db Expert option: Select the file that defines the elements known to UFF
Library
Type: Multiple Choice UFF [UFF, UFF4MOF, UFF4MOF-II] Force field library Selects the used parameter library.
Verbosity
Type: Multiple Choice Silent [Silent, Normal, Verbose, VeryVerbose] Controls the verbosity of the engine.