CenterOfMassMove Class Reference

A derived class which performs a simple displacement of the center of mass of the entire wordline for a particle. More...

#include <move.h>

Inheritance diagram for CenterOfMassMove:

Collaboration diagram for CenterOfMassMove:

Public Member Functions
	CenterOfMassMove (Path &, ActionBase *, MTRand &, ensemble _operateOnConfig=ANY)
	Constructor.
	~CenterOfMassMove ()
	Destructor.
bool	attemptMove ()
	Performs a Center of Mass move. More...
string	getName ()
	return the move name
Public Member Functions inherited from MoveBase
	MoveBase (Path &, ActionBase *, MTRand &, ensemble _operateOnConfig=ANY, bool _varLength=false)
	Move naming conventions: More...
virtual	~MoveBase ()
	Destructor.
double	getAcceptanceRatio ()
	Get the acceptance ratio.
double	getTotAcceptanceRatio ()
	Get the total acceptance ratio.
double	getAcceptanceRatioLevel (int n)
	Get the acceptance ratio by level.
int	getNumAttempted ()
	Get the number of moves attempted.
int	getNumAccepted ()
	Get the number of moves accepted.
int	getNumAttemptedLevel (int n)
	Get the number of moves attempted by level.
int	getNumAcceptedLevel (int n)
	Get the number of moves accepted by level.
void	resetTotAccept ()
	Reset the total accepted counter.
void	resetAccept ()
	Reset the number accepted counter.

Static Public Attributes
static const string	name

Additional Inherited Members
Data Fields inherited from MoveBase
ensemble	operateOnConfig
	What configurations do we operate on?
bool	variableLength
	Does the move have a variable length?
string	name1
Protected Member Functions inherited from MoveBase
virtual void	keepMove ()
	Keep the move. More...
dVec	newStagingPosition (const beadLocator &, const beadLocator &, const int, const int)
	Returns a new staging position which will exactly sample the kinetic action. More...
dVec	newStagingPosition (const beadLocator &, const beadLocator &, const int, const int, iVec &)
	Returns a new staging position which will exactly sample the kinetic action in different winding sectors. More...
iVec	sampleWindingSector (const beadLocator &, const beadLocator &, const int, double &)
	Obtain a winding sector for a stage-like move. More...
iVec	getWindingNumber (const beadLocator &, const beadLocator &)
	Find the winding number for a path between two beads. More...
dVec	newFreeParticlePosition (const beadLocator &)
	Generates a new position, which exactly samples the free particle density matrix. More...
dVec	newBisectionPosition (const beadLocator &, const int)
	Returns a new bisection position which will exactly sample the kinetic action. More...
void	printMoveState (string)
void	checkMove (int, double)
Protected Attributes inherited from MoveBase
Path &	path
	A reference to the paths.
ActionBase *	actionPtr
	A base pointer to the action.
MTRand &	random
	A reference to the RNG.
bool	success
	Did we sucessfully perform a move?
uint32	numAccepted
	The number of accepted moves.
uint32	numAttempted
	The number of attempted moves.
int	numToMove
	The number of particles moved.
int	numLevels
Array< uint32, 1 >	numAcceptedLevel
	The number of moves accepted at each level.
Array< uint32, 1 >	numAttemptedLevel
	The number of moves attempted at each level.
Array< dVec, 1 >	originalPos
	The original particle positions.
Array< dVec, 1 >	newPos
	New particle positions.
vector< iVec >	winding
	The winding vectors
vector< int >	windingSector
	Used to index different winding sectors.
vector< double >	cumrho0
	Used for tower-sampling winding sectors.
int	maxWind
	The largest winding number.
int	numWind
	The total number of winding vectors.
double	oldAction
	The original potential action.
double	newAction
	The new potential action.
double	deltaAction
	The action difference.
double	sqrt2LambdaTau
	sqrt(2 * Lambda * tau)
double	sqrtLambdaTau
	sqrt(Lambda * tau)
beadLocator	nBeadIndex
	Neighbor bead index.
dVec	neighborPos
	Staging neighbor position.
dVec	newRanPos
	Staing random position.
double	newK
double	oldK
	The old and new kinetic action.
double	newV
double	oldV
	The old and new potential action.
Static Protected Attributes inherited from MoveBase
static uint32	totAccepted = 0
	The total number of moves accepted.
static uint32	totAttempted = 0
	The total number of moves attempted.

Detailed Description

A derived class which performs a simple displacement of the center of mass of the entire wordline for a particle.

Definition at line 247 of file move.h.

Member Function Documentation

attemptMove()

bool CenterOfMassMove::attemptMove ( )

virtual

Performs a Center of Mass move.

For each active particle, we move the center of mass of its wordline by a fixed random amount.

Implements MoveBase.

Definition at line 1126 of file move.cpp.

                                   {
 
    success = false;
 
    /* Only perform a move if we have beads */
    if (path.worm.getNumBeadsOn() == 0) 
        return success;
    
    int startSlice = 0;
    /* If there are broken wordlines, choose between starting and ending bead*/
    if( (path.breakSlice > 0) && (random.rand() < 0.5) )
        startSlice = path.numTimeSlices-1;
 
    /* We don't bother performing a center of mass move, unless we have at 
     * least one bead on startSlice */
    if (path.numBeadsAtSlice(startSlice) == 0)
        return false;
 
    checkMove(0,0.0);
 
    /* The initial bead */
    beadLocator firstBead;
    firstBead = startSlice,random.randInt(path.numBeadsAtSlice(startSlice)-1);
 
    bool startSubregionA,startSubregionB,endSubregionA,endSubregionB;
 
    /* Now we traverse the path backwards, until we find 1 of two
     * possibilities, either we reach a null bead, or we wrap around */
    startBead = firstBead;
    if (!all(path.prev(startBead)==XXX)) {
        do {
            startBead = path.prev(startBead);
        } while (!all(path.prev(startBead)==firstBead) && !all(path.prev(startBead)==XXX));
    }
 
    /* Get a closed worldline */
    if (all(path.prev(startBead)==firstBead)) {
        startBead = firstBead;
        endBead = path.prev(startBead);
    }
    /* Otherwise, find the end bead */
    else {
        endBead = firstBead;
        if (!all(path.next(endBead)==XXX)) {
            do {
                endBead = path.next(endBead);
            } while(!all(path.next(endBead)==XXX));
        }
    }
 
    int wlLength = 0;
    beadLocator beadIndex;
 
    /* Make sure the worldline to be moved is shorter than the number of time
     * slices */
    beadIndex = startBead;
    do {
        ++wlLength;
        beadIndex = path.next(beadIndex);
    } while (!all(beadIndex==path.next(endBead)));
 
    if (wlLength > constants()->numTimeSlices())
        return false;
 
    /* Increment the number of center of mass moves and the total number
     * of moves */
    numAttempted++;
    totAttempted++;
 
    /* The random shift that will be applied to the center of mass*/
    for (int i = 0; i < NDIM; i++) 
        originalPos(0)[i] = constants()->comDelta()*(-0.5 + random.rand());
 
    /* Here we test to see if any beads are placed outside the box (if we
     * don't have periodic boundary conditions).  If that is the case,
     * we don't continue */
    dVec pos;
    if (int(sum(path.boxPtr->periodic)) != NDIM) {
        beadIndex = startBead;
        do {
            pos = path(beadIndex) + originalPos(0);
            path.boxPtr->putInBC(pos);
            for (int i = 0; i < NDIM; i++) {
                if ((pos[i] < -0.5*path.boxPtr->side[i]) || (pos[i] >= 0.5*path.boxPtr->side[i]))
                    return false;
            }
            beadIndex = path.next(beadIndex);
        } while (!all(beadIndex==path.next(endBead)));
    }
 
    /* Determine the old potential action of the path */
     oldAction = actionPtr->potentialAction(startBead,endBead);
 
    /* Go through the worldline and update the position of all the beads */
    beadIndex = startBead;
    startSubregionA = false;
    startSubregionB = false;
    endSubregionA = false;
    endSubregionB = false;
    do {
        /* Check if bead is in subregion A or B */
        if ((constants()->spatialSubregionOn())&&(!(startSubregionA||startSubregionB))){
            startSubregionA = path.inSubregionA(beadIndex);
            startSubregionB = path.inSubregionB(beadIndex);
        }
        pos = path(beadIndex) + originalPos(0);
        path.boxPtr->putInBC(pos);
        path.updateBead(beadIndex,pos);
        if ((constants()->spatialSubregionOn())&&(!(endSubregionA||endSubregionB))){
            endSubregionA = path.inSubregionA(beadIndex);
            endSubregionB = path.inSubregionB(beadIndex);
        }
        beadIndex = path.next(beadIndex);
    } while (!all(beadIndex==path.next(endBead)));
    
    if ( (startSubregionA && endSubregionB)|| (startSubregionB && endSubregionA) ){
        undoMove();
        checkMove(2,0.0);
    } else{
        /* Get the new potential action of the path */
        newAction = actionPtr->potentialAction(startBead,endBead);
 
        /* The metropolis acceptance step */
        if (random.rand() < exp(-(newAction - oldAction)))  {
            keepMove();
            checkMove(1,newAction-oldAction);
        }
        else {
            undoMove();
            checkMove(2,0.0);
        }
    }
 
    return success;
}

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

• include/move.h
• src/move.cpp