AmoebaPiTorsionForce¶

class
simtk.openmm.openmm.
AmoebaPiTorsionForce
(*args)¶ This class implements the Amoeba pitorsion interaction.
To use it, create an AmoebaPiTorsionForce object then call addPiTorsion() once for each torsion. After a torsion has been added, you can modify its force field parameters by calling setPiTorsionParameters(). This will have no effect on Contexts that already exist unless you call updateParametersInContext().

__init__
(self) → AmoebaPiTorsionForce¶ __init__(self, other) > AmoebaPiTorsionForce
Create an AmoebaPiTorsionForce.
Methods
__init__
((self) > AmoebaPiTorsionForce)__init__(self, other) > AmoebaPiTorsionForce addPiTorsion
((self, particle1, particle2, ...)Add a torsion term to the force field. getForceGroup
((self) > int)Get the force group this Force belongs to. getNumPiTorsions
((self) > int)Get the number of pi torsion terms in the potential function getPiTorsionParameters
(self, index)Get the force field parameters for a torsion term. setForceGroup
(self, group)Set the force group this Force belongs to. setPiTorsionParameters
(self, index, ...)Set the force field parameters for a pi torsion term. setUsesPeriodicBoundaryConditions
(self, periodic)Set whether this force should apply periodic boundary conditions when calculating displacements. updateParametersInContext
(self, context)Update the pertorsion parameters in a Context to match those stored in this Force object. usesPeriodicBoundaryConditions
((self) > bool)Returns whether or not this force makes use of periodic boundary conditions. 
getNumPiTorsions
(self) → int¶ Get the number of pi torsion terms in the potential function

addPiTorsion
(self, particle1, particle2, particle3, particle4, particle5, particle6, k) → int¶ Add a torsion term to the force field.
Parameters:  particle1 (int) – the index of the first particle connected by the torsion
 particle2 (int) – the index of the second particle connected by the torsion
 particle3 (int) – the index of the third particle connected by the torsion
 particle4 (int) – the index of the fourth particle connected by the torsion
 particle5 (int) – the index of the fifth particle connected by the torsion
 particle6 (int) – the index of the sixth particle connected by the torsion
 k (double) – the force constant for the torsion
Returns: the index of the torsion that was added
Return type: int

getPiTorsionParameters
(self, index)¶ Get the force field parameters for a torsion term.
Parameters: index (int) – the index of the torsion for which to get parameters Returns:  particle1 (int) – the index of the first particle connected by the torsion
 particle2 (int) – the index of the second particle connected by the torsion
 particle3 (int) – the index of the third particle connected by the torsion
 particle4 (int) – the index of the fourth particle connected by the torsion
 particle5 (int) – the index of the fifth particle connected by the torsion
 particle6 (int) – the index of the sixth particle connected by the torsion
 k (double) – the force constant for the torsion

setPiTorsionParameters
(self, index, particle1, particle2, particle3, particle4, particle5, particle6, k)¶ Set the force field parameters for a pi torsion term.
Parameters:  index (int) – the index of the torsion for which to set parameters
 particle1 (int) – the index of the first particle connected by the torsion
 particle2 (int) – the index of the second particle connected by the torsion
 particle3 (int) – the index of the third particle connected by the torsion
 particle4 (int) – the index of the fourth particle connected by the torsion
 particle5 (int) – the index of the fifth particle connected by the torsion
 particle6 (int) – the index of the sixth particle connected by the torsion
 k (double) – the force constant for the torsion

updateParametersInContext
(self, context)¶ Update the pertorsion parameters in a Context to match those stored in this Force object. This method provides an efficient method to update certain parameters in an existing Context without needing to reinitialize it. Simply call setPiTorsionParameters() to modify this object’s parameters, then call updateParametersInContext() to copy them over to the Context.
The only information this method updates is the values of pertorsion parameters. The set of particles involved in a torsion cannot be changed, nor can new torsions be added.

setUsesPeriodicBoundaryConditions
(self, periodic)¶ Set whether this force should apply periodic boundary conditions when calculating displacements. Usually this is not appropriate for bonded forces, but there are situations when it can be useful.

usesPeriodicBoundaryConditions
(self) → bool¶ Returns whether or not this force makes use of periodic boundary conditions.
Returns: true if force uses PBC and false otherwise Return type: bool

__copy__
(self) → Force¶

getForceGroup
(self) → int¶ Get the force group this Force belongs to.

setForceGroup
(self, group)¶ Set the force group this Force belongs to.
Parameters: group (int) – the group index. Legal values are between 0 and 31 (inclusive).
