Package etomica.integrator.mcmove

Class MCMove

java.lang.Object

etomica.integrator.mcmove.MCMove

Direct Known Subclasses:

MCMoveBox, MCMoveGeometricClusterRestrictedGE, MCMoveMoleculeExchange, MCMoveStep, MCMoveSwapCluster, MCMoveSwapConfiguration

public abstract class MCMove
extends java.lang.Object

Parent class for all elementary Monte Carlo move classes, as used by IntegratorMC class. Includes actions needed to complete trial move, and reports numbers needed to determine if move is accepted.
Subclasses should set value of nominal frequency and perParticleFrequency flag if the move is to be performed at a rate different from the defaults. Default nominalFrequency is 100, and perParticleFrequency is false.

Field Summary

Fields

Modifier and Type	Field	Description
protected MCMoveTracker	moveTracker
protected int	nominalFrequency	Value giving nominal frequency for performing this move.
protected PotentialMaster	potential

Constructor Summary

Constructors

Constructor	Description
MCMove(PotentialMaster potentialMaster)
MCMove(PotentialMaster potentialMaster, MCMoveTracker acceptanceTracker)

Method Summary

Modifier and Type	Method	Description
abstract void	acceptNotify()	Method called by IntegratorMC in the event that the most recent trial is accepted.
abstract AtomIterator	affectedAtoms(Box box)	Returns an iterator that yields the atoms that were affected by the trial move the last time doTrial was invoked (regardless of whether the move was accepted).
abstract boolean	doTrial()	Method to perform trial move.
abstract double	energyChange(Box box)	Returns the change in the energy of the given box that results from the trial move.
abstract double	getChi(double temperature)	Chi is the parameter within standard Metropolis Monte Carlo.
int	getNominalFrequency()	Returns a nominal, unnormalized frequency for performing this move, relative to the other moves that have been added to the integrator.
MCMoveTracker	getTracker()
abstract void	rejectNotify()	Method called by IntegratorMC in the event that the most recent trial move is rejected.
void	setTracker(MCMoveTracker newTracker)
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

potential

protected final PotentialMaster potential

nominalFrequency

protected int nominalFrequency

Value giving nominal frequency for performing this move. Default is 100, but may be given a different value by subclasses.

moveTracker

protected MCMoveTracker moveTracker

Constructor Detail

MCMove

public MCMove(PotentialMaster potentialMaster)

Parameters:

potentialMaster - the potential master that move can use to calculate energy

MCMove

public MCMove(PotentialMaster potentialMaster,
              MCMoveTracker acceptanceTracker)

Parameters:

potentialMaster - the potential master that move can use to calculate energy

Method Detail

setTracker

public void setTracker(MCMoveTracker newTracker)

doTrial

public abstract boolean doTrial()

Method to perform trial move. Returns false if the trial could not be attempted, for example if there were no molecules in the box and the trial is designed to displace an atom; returns true otherwise.

getChi

public abstract double getChi(double temperature)

Chi is the parameter within standard Metropolis Monte Carlo. The probability of accepting the move is given by min(1,chi).

Parameters:

temperature - used to compute chi

Returns:

chi

acceptNotify

public abstract void acceptNotify()

Method called by IntegratorMC in the event that the most recent trial is accepted.

rejectNotify

public abstract void rejectNotify()

Method called by IntegratorMC in the event that the most recent trial move is rejected. This method should cause the system to be restored to the condition before the most recent call to doTrial.

affectedAtoms

public abstract AtomIterator affectedAtoms(Box box)

Returns an iterator that yields the atoms that were affected by the trial move the last time doTrial was invoked (regardless of whether the move was accepted). This information usually is not needed, but it is available in cases where required by objects that perform some activity while the move is in progress, or need to update after the move is completed. Such objects can receive notification of the move's completion by registering with the IntegratorMC as MCMoveEventListeners. If the move caused an atom to be removed from the box, it will not be returned because that Atom is not considered an affected Atom.

energyChange

public abstract double energyChange(Box box)

Returns the change in the energy of the given box that results from the trial move. Should be called only after lnProbabilityRatio(); returns Double.NaN if invoked between calls to doTrial and lnProbabilityRatio.

getTracker

public MCMoveTracker getTracker()

getNominalFrequency

public final int getNominalFrequency()

Returns a nominal, unnormalized frequency for performing this move, relative to the other moves that have been added to the integrator. Each move is performed (on average) an amount in proportion to this frequency. Moves having the same frequency are performed with equal likelihood. Default value is 100, but this may be overridden by the subclass. The nominal frequency cannot be changed, as it is used only to advise the integrator when the move is added to it. Adjustment of the move frequency (if the nominal value is not desired) can be accomplished via the setFrequency method of IntegratorMC.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object