AmoebaPiTorsionForce

class simtk.openmm.openmm.AmoebaPiTorsionForce(*args)

This class implements the Amoeba pi-torsion 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)

__init__(self, other) -> AmoebaPiTorsionForce Create an AmoebaPiTorsionForce.

addPiTorsion(self, particle1, particle2, …)

Add a torsion term to the force field.

getForceGroup(self)

Get the force group this Force belongs to.

getNumPiTorsions(self)

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 per-torsion parameters in a Context to match those stored in this Force object.

usesPeriodicBoundaryConditions(self)

Returns whether or not this force makes use of periodic boundary conditions.

Attributes

thisown

The membership flag
property thisown

The membership flag

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 per-torsion 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 per-torsion 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).