PeriodicTorsionForce Class Reference

This class implements an interaction between groups of four particles that varies periodically with the torsion angle between them. More...

Inheritance diagram for PeriodicTorsionForce:

List of all members.

Public Member Functions
def	getNumTorsions
	getNumTorsions(self) -> int
def	addTorsion
	addTorsion(self, particle1, particle2, particle3, particle4, periodicity, phase, k) -> int
def	getTorsionParameters
	Get the force field parameters for a periodic torsion term.
def	setTorsionParameters
	Set the force field parameters for a periodic torsion term.
def	updateParametersInContext
	Update the per-torsion parameters in a Context to match those stored in this Force object.
def	usesPeriodicBoundaryConditions
	usesPeriodicBoundaryConditions(self) -> bool
def	__init__
	__init__(self) -> PeriodicTorsionForce __init__(self, other) -> PeriodicTorsionForce
Public Attributes
	this

---

Detailed Description

This class implements an interaction between groups of four particles that varies periodically with the torsion angle between them.

To use it, create a PeriodicTorsionForce object then call addTorsion() once for each torsion. After a torsion has been added, you can modify its force field parameters by calling setTorsionParameters(). This will have no effect on Contexts that already exist unless you call updateParametersInContext().

---

Constructor & Destructor Documentation

def __init__	(		self,
			args
	)

__init__(self) -> PeriodicTorsionForce __init__(self, other) -> PeriodicTorsionForce

Create a PeriodicTorsionForce.

---

Member Function Documentation

def addTorsion	(		self,
			particle1,
			particle2,
			particle3,
			particle4,
			periodicity,
			phase,
			k
	)

addTorsion(self, particle1, particle2, particle3, particle4, periodicity, phase, k) -> int

Add a periodic torsion term to the force field.

Parameters:

particle1	(int) the index of the first particle forming the torsion
particle2	(int) the index of the second particle forming the torsion
particle3	(int) the index of the third particle forming the torsion
particle4	(int) the index of the fourth particle forming the torsion
periodicity	(int) the periodicity of the torsion
phase	(double) the phase offset of the torsion, measured in radians
k	(double) the force constant for the torsion

Returns:

(int) the index of the torsion that was added

def getNumTorsions

(

self

)

getNumTorsions(self) -> int

Get the number of periodic torsion terms in the potential function

def getTorsionParameters	(		self,
			index
	)

Get the force field parameters for a periodic torsion term.

Parameters:

index

(int) the index of the torsion for which to get parameters

Returns:

(int) the index of the first particle forming the torsion

(int) the index of the second particle forming the torsion

(int) the index of the third particle forming the torsion

(int) the index of the fourth particle forming the torsion

(int) the periodicity of the torsion

(double) the phase offset of the torsion, measured in radians

(double) the force constant for the torsion

def setTorsionParameters	(		self,
			index,
			particle1,
			particle2,
			particle3,
			particle4,
			periodicity,
			phase,
			k
	)

Set the force field parameters for a periodic torsion term.

Parameters:

index	(int) the index of the torsion for which to set parameters
particle1	(int) the index of the first particle forming the torsion
particle2	(int) the index of the second particle forming the torsion
particle3	(int) the index of the third particle forming the torsion
particle4	(int) the index of the fourth particle forming the torsion
periodicity	(int) the periodicity of the torsion
phase	(double) the phase offset of the torsion, measured in radians
k	(double) the force constant for the torsion

def 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 setTorsionParameters() 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.

def usesPeriodicBoundaryConditions

(

self

)

usesPeriodicBoundaryConditions(self) -> bool

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

Returns:

(bool) true if force uses PBC and false otherwise

Reimplemented from Force.

---

Member Data Documentation

this

Reimplemented from Force.

---

The documentation for this class was generated from the following file:

• openmm.py