CollectiveVariable Class Reference

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Detailed Description

Abstract interface for a collective variable

All C++ implementations of collective variables inherit from this class. A CollectiveVariable is an extension of a ForceCompute, and can compute forces.

The force generated by a collective variable (i.e. its negative derivative with respect to particle positions) must be multiplied by a bias factor (the partial derivative of the biasing potential with respect to the collective variable). The bias factor is set using the method setBiasFactor().

Collective variables should have a potential energy of zero, since they are not directly added to the Hamiltonian (only via the biasing potential). Instead, the value of the collective variable can be queried using getCurrentValue().

Inheritance diagram for CollectiveVariable:

List of all members.

Public Member Functions
	CollectiveVariable (boost::shared_ptr< SystemDefinition > sysdef, const std::string &name)
virtual void	computeForces (unsigned int timestep)=0
virtual Scalar	getCurrentValue (unsigned int timestep)=0
virtual void	setBiasFactor (Scalar bias)
std::string	getName ()

Protected Attributes
Scalar	m_bias
std::string	m_cv_name

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Constructor & Destructor Documentation

CollectiveVariable	(	boost::shared_ptr< SystemDefinition >	sysdef,
		const std::string &	name
	)

Constructs a collective variable

Parameters:

sysdef	The system definition
name	The name of this collective variable

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Member Function Documentation

virtual void computeForces ( unsigned int  timestep )

pure virtual

Compute the forces for this collective variable. The force that is written to the force arrays must be multiplied by the bias factor.

Parameters:

timestep

The current value of the time step

Implemented in LamellarOrderParameter, and CollectiveVariableWrap.

virtual Scalar getCurrentValue ( unsigned int  timestep )

pure virtual

Returns the current value of the collective variable

Parameters:

timestep

The currnt value of the timestep

Implemented in LamellarOrderParameter, and CollectiveVariableWrap.

std::string getName ( )

inline

Returns the name of the collective variable

virtual void setBiasFactor ( Scalar  bias )

inlinevirtual

Set the current value of the bias factor. This routine has to be called before force evaluation by the integrator.

Parameters:

bias	The value that multiplies the force

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

• CollectiveVariable.h
• CollectiveVariable.cc