OneBodyDensityMatrixEstimator Class Reference

Compute the one body density matrix n(r) which can be used to find the momentum distribution function and structure factor. More...

#include <estimator.h>

Inheritance diagram for OneBodyDensityMatrixEstimator:

Collaboration diagram for OneBodyDensityMatrixEstimator:

Public Member Functions
	OneBodyDensityMatrixEstimator (Path &, ActionBase *, const MTRand &, double, int _frequency=20, string _label="obdm")
	Constructor. More...
	~OneBodyDensityMatrixEstimator ()
	Destructor.
void	sample ()
	Sample the OBDM. More...
void	outputFooter ()
	For the one body density matrix estimator, we would like to output the acceptance information for the accumulate trial move.
string	getName () const
	Get the name of the estimator.
Public Member Functions inherited from EstimatorBase
	EstimatorBase (const Path &_path, ActionBase *_actionPtr, const MTRand &_random, double _maxR, int _frequency=1, string _label="")
	Constructor. More...
virtual	~EstimatorBase ()
	Destructor.
void	reset ()
	Reset numAccumulated and the estimator to 0.
void	restart (const uint32, const uint32)
	Restart the measurment process from a previous state.
virtual void	output ()
	Output the estimator value to disk. More...
virtual void	outputFlat ()
	Output a flat estimator value to disk. More...
bool	baseSample ()
	Determine the basic sampling condition. More...
uint32	getTotNumAccumulated () const
	Get the total number of accumulated measurments.
uint32	getNumAccumulated () const
	Get the number of accumulated measurements since the last reset.
uint32	getNumSampled () const
	Get the number of samples since the last reset.
void	prepare ()
	Prepare the estimator for i/o. More...
void	addEndLine ()
	Add a carriage return to estimator files.
void	appendLabel (string append)
	Append to default label. More...
string	getLabel () const
	Get the estimator label.

Static Public Attributes
static const string	name

Additional Inherited Members
Protected Member Functions inherited from EstimatorBase
void	initialize (int)
	Initialize estimator. More...
void	initialize (vector< string >)
	Initialize estimator. More...
Protected Attributes inherited from EstimatorBase
const Path &	path
	A constant reference to the paths.
ActionBase *	actionPtr
	A pointer to the action.
MTRand	random
double	maxR
fstream *	outFilePtr
	The output fie.
map< string, int >	estIndex
	Map estimator labels to indices.
Array< double, 1 >	estimator
	The estimator array.
Array< double, 1 >	norm
	The normalization factor for each estimator.
int	numEst
	The number of individual quantities measured.
int	frequency
	The frequency at which we accumulate.
int	startSlice
	Where imaginary time averages begin.
int	endSlice
	Where imaginary time averages end.
int	endDiagSlice
	Where imaginary time averages end for diagonal estimiators.
vector< double >	sliceFactor
	Used to properly incorporate end affects.
string	label
	The label used for the output file.
uint32	numSampled
	The number of times we have sampled.
uint32	numAccumulated
	The number of accumulated values.
uint32	totNumAccumulated
	The total number of accumulated values.
int	numBeads0
	The target number of beads for the canonical ensemble.
bool	diagonal
	Is this a diagonal estimator?
bool	endLine
	Should we output a carriage return?
bool	canonical
	Are we in the canonical ensemble?
string	header
	The data file header.

Detailed Description

Compute the one body density matrix n(r) which can be used to find the momentum distribution function and structure factor.

We use a reference to the global random number generator, and thus this estimator can effect final results. We also need a non-constant local reference to the Path which is used for temporary updates.

Definition at line 644 of file estimator.h.

Constructor & Destructor Documentation

OneBodyDensityMatrixEstimator()

OneBodyDensityMatrixEstimator::OneBodyDensityMatrixEstimator	(	Path &	_path,
		ActionBase *	_actionPtr,
		const MTRand &	_random,
		double	_maxR,
		int	_frequency = 20,
		string	_label = "obdm"
	)

Constructor.

The one body density matrix estimator is initialized. We measure NOBDMSEP positions, out to the maximum separation in the sample (which may depend on the type of simulation cell).

Definition at line 2256 of file estimator.cpp.

                                       : 
    EstimatorBase(_path,_actionPtr,_random,_maxR,_frequency,_label),
    lpath(_path)
{
 
    sqrt2LambdaTau = sqrt(2.0 * constants()->lambda() * constants()->tau());
 
    /* We chooose the maximum separation to be sqrt(NDIM)*min(L)/2 */
    dR = 0.5*sqrt(sum(path.boxPtr->periodic))*(blitz::min(path.boxPtr->side)) / (1.0*NOBDMSEP);
 
    /* This is an off-diagonal estimator*/
    initialize(NOBDMSEP);
    diagonal = false;
 
    /* The header is the first line which contains the spatial separations */
    header = str(format("#%15.3E") % 0.0);
    for (int n = 1; n < NOBDMSEP; n++) 
        header.append(str(format("%16.3E") % (n*dR)));
 
    numReps = 5;
    norm = 1.0 / (1.0*numReps);
}

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Member Function Documentation

sample()

void OneBodyDensityMatrixEstimator::sample ( )

virtual

Sample the OBDM.

We overload the sample method for the one body density matrix as we only want to measure when the gap is not too large, otherwise we will be dominated by tiny close probabilities.

!!NB!! We only measure the OBDM when the tail is on an even time slice

Reimplemented from EstimatorBase.

Definition at line 2296 of file estimator.cpp.

                                           {
    numSampled++;
    if ( frequency && 
         ((numSampled % frequency) == 0) &&
         (path.worm.isConfigDiagonal == diagonal) &&
         (path.worm.gap > 0) && (path.worm.gap <= constants()->Mbar())  &&
         ( (lpath.worm.tail[0] % 2) == 0) ) {
 
        /* If we are canonical, we want the closed configuration to be close
         * to our ideal one */
        if ( (!canonical) || 
             (abs(path.worm.getNumBeadsOn()+path.worm.gap-numBeads0) <= 2) ) {
            totNumAccumulated++;
            numAccumulated++;
            accumulate();
        }
    }
}

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

• include/estimator.h
• src/estimator.cpp