AmoebaPiTorsionForce¶

class
OpenMM::
AmoebaPiTorsionForce
¶ This class implements the Amoeba pitorsion interaction.
To use it, create an
AmoebaPiTorsionForce
object then calladdPiTorsion()
once for each torsion. After a torsion has been added, you can modify its force field parameters by callingsetPiTorsionParameters()
. This will have no effect on Contexts that already exist unless you callupdateParametersInContext()
.Methods
AmoebaPiTorsionForce
Create an AmoebaPiTorsionForce
.getNumPiTorsions
Get the number of pi torsion terms in the potential function addPiTorsion
Add a torsion term to the force field. getPiTorsionParameters
Get the force field parameters for a torsion term. setPiTorsionParameters
Set the force field parameters for a pi torsion term. updateParametersInContext
Update the pertorsion parameters in a Context
to match those stored in thisForce
object.setUsesPeriodicBoundaryConditions
Set whether this force should apply periodic boundary conditions when calculating displacements. usesPeriodicBoundaryConditions
Returns whether or not this force makes use of periodic boundary conditions. 
AmoebaPiTorsionForce
()¶ Create an
AmoebaPiTorsionForce()
.

int
getNumPiTorsions
() const¶ Get the number of pi torsion terms in the potential function

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

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

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

void
updateParametersInContext
(Context &context)¶ Update the pertorsion parameters in a
Context
to match those stored in thisForce
object. This method provides an efficient method to update certain parameters in an existingContext
without needing to reinitialize it. Simply callsetPiTorsionParameters()
to modify this object’s parameters, then callupdateParametersInContext()
to copy them over to theContext
.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.

void
setUsesPeriodicBoundaryConditions
(bool 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.

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