class representing the phonon scattering matrix. More...

#include <ph_scattering_matrix.h>

Inheritance diagram for PhScatteringMatrix:

Collaboration diagram for PhScatteringMatrix:

Public Member Functions
	PhScatteringMatrix (Context &context_, StatisticsSweep &statisticsSweep_, BaseBandStructure &innerBandStructure_, BaseBandStructure &outerBandStructure_, PhononH0 *phononH0_=nullptr)
	Default constructor. More...

Public Member Functions inherited from BasePhScatteringMatrix
	BasePhScatteringMatrix (Context &context_, StatisticsSweep &statisticsSweep_, BaseBandStructure &innerBandStructure_, BaseBandStructure &outerBandStructure_)
	Constructor that just calls the constructor of scattering matrix.

Public Member Functions inherited from ScatteringMatrix
	ScatteringMatrix (Context &context_, StatisticsSweep &statisticsSweep_, BaseBandStructure &innerBandStructure_, BaseBandStructure &outerBandStructure_)
	Scattering matrix constructor. More...

	ScatteringMatrix ()
	Default constructor.

void	setup ()
	This method needs to be called right after the constructor. More...

VectorBTE	diagonal ()
	Returns the diagonal matrix elements. More...

double &	operator() (const int &row, const int &col)
	Get and set operator. More...

VectorBTE	offDiagonalDot (VectorBTE &inPopulation)
	Computes the product Af - diagonal(A)f where A is the scattering matrix and f is the vector of quasiparticle populations.

std::vector< VectorBTE >	offDiagonalDot (std::vector< VectorBTE > &inPopulations)

VectorBTE	dot (VectorBTE &inPopulation)
	Computes the product A*f where A is the scattering matrix and f is the vector of quasiparticle populations.

std::vector< VectorBTE >	dot (std::vector< VectorBTE > &inPopulations)

VectorBTE	getSingleModeTimes ()
	Call to obtain the single-particle relaxation times of the systems. More...

VectorBTE	getLinewidths ()
	Converts symmetrized internal scattering matrix diagonal to linewidths and returns the result. More...

void	setLinewidths (VectorBTE &linewidths)
	Call to set the single-particle linewidths. More...

VectorBTE	getSingleModeTimes (const VectorBTE &anyInternalDiagonal)
	Call to obtain the single-particle relaxation times of the systems given any internal diagonal like object – (basically, the linewidths but potentially scaled by some symmetrization factor) More...

VectorBTE	getLinewidths (const VectorBTE &anyInternalDiagonal)
	Call to obtain the single-particle linewidths. More...

void	a2Omega ()
	Converts the scattering matrix from the form A to the symmetrised Omega. More...

void	omega2A ()
	The inverse of a2Omega, converts the matrix Omega to A.

std::tuple< Eigen::VectorXd, ParallelMatrix< double > >	diagonalize (int numEigenvalues=0)
	Diagonalize the scattering matrix. More...

int	getSMatrixIndex (BteIndex &bteIndex, CartIndex &cartIndex)
	Function to combine a BTE index and a cartesian index into one index of the scattering matrix. More...

std::tuple< BteIndex, CartIndex >	getSMatrixIndex (const int &iMat)
	Function to split a scattering matrix index (on rows/columns of S) into a BTE index and a cartesian index. More...

void	symmetrize ()
	Reinforce the condition that the matrix is symmetric.

void	relaxonsToJSON (const std::string &fileName, const Eigen::VectorXd &eigenvalues)
	Output relaxons scattering matrix quantities to file (particularly the tau values) Jenny's note: However, I have a feeling this should be elsewhere, as we're actually passing the eigenvalues back into this function. More...

std::vector< std::tuple< int, int > >	getAllLocalStates ()
	Call the underlying PMatrix function to return the iterator of all elements of the matrix which are local. More...

void	outputToHDF5 (const std::string &outFileName)
	Outputs the matrix to an hdf5 file. More...

Protected Member Functions
void	builder (std::shared_ptr< VectorBTE > linewidth, std::vector< VectorBTE > &inPopulations, std::vector< VectorBTE > &outPopulations) override
	Method that actually computes the scattering matrix. More...

Protected Member Functions inherited from ScatteringMatrix
std::vector< std::tuple< std::vector< int >, int > >	getIteratorWavevectorPairs (const bool &rowMajor=false)
	Returns a vector of pairs of wavevector indices to iterate over during the construction of the scattering matrix. More...

void	degeneracyAveragingLinewidths (std::shared_ptr< VectorBTE > linewidth)
	Performs an average of the linewidths over degenerate states. More...

Eigen::MatrixXd	precomputeOccupations (BaseBandStructure &bandStructure)
	Function to precompute particle populations before scattering rates are calculated. More...

std::vector< int >	getExcludeIndices (BaseBandStructure &bandStructure)
	Method which for a phonon bandstructure returns the indices to be discarded in a phonon calculation due to very low phonon frequencies. More...

void	setMatrixCase (std::shared_ptr< VectorBTE > linewidth, std::vector< VectorBTE > &inPopulations, std::vector< VectorBTE > &outPopulations)

void	addRateToMatrix (const Context &context, double linewidthRate, double matrixRate, int iCalc, int is1, int is2Irr, int iBte1, int iBte2, const Particle &p1, const Particle &p2, const Eigen::Matrix3d &rotation, std::shared_ptr< VectorBTE > linewidth, const std::vector< VectorBTE > &inPopulations, std::vector< VectorBTE > &outPopulations)
	Method to add scattering rate to matrix and linewidth containers. More...

void	enforceDetailedBalance ()
	A function to fix the linewidths to agree with the off diagonal elements, to enforce finding the special eigenvectors.

void	replaceMatrixLinewidths ()
	Replace the linewidths of the scatterng matrix with the supplied VectorBTE values.

std::tuple< BaseBandStructure , BaseBandStructure >	getStateBandStructures (const BteIndex &iBte1, const BteIndex &iBte2)
	Returns a tuple of final and initial particles for a give state. More...

std::tuple< int, int >	coupledToBandStructureIndices (const int &iBte1, const int &iBte2, const Particle &p1, const Particle &p2)
	If we have a coupled scattering matrix, we need to shift the matrix element indices back to those associated with ph and el bandstructures before accessing their quantities. More...

template<size_t n>
void	addUNRates (int iCalc, int iBte, double rate, const std::array< Point, n > &crysPoints, auto momentumConsExpr)
	Generic function to add UN times to their containers. More...

Protected Attributes
PhononH0 *	phononH0

Protected Attributes inherited from ScatteringMatrix
Context &	context

StatisticsSweep &	statisticsSweep

BaseBandStructure &	innerBandStructure

BaseBandStructure &	outerBandStructure

enum MatrixCase	matrixCase

bool	constantRTA = false

bool	highMemory = true

bool	outputUNTimes = false

double	boundaryLength

bool	doBoundary

bool	isMatrixOmega = false

bool	isCoupled = false

std::function< std::tuple< long, long >long, long, const Particle &, const Particle &)>	shiftToCoupledIndices

std::shared_ptr< VectorBTE >	internalDiagonal

std::shared_ptr< VectorBTE >	internalDiagonalUmklapp

std::shared_ptr< VectorBTE >	internalDiagonalNormal

ParallelMatrix< double >	theMatrix

int	numStates

int	numCalculations

int	dimensionality_

int	numElStates = 0

std::vector< int >	excludeIndices

Friends
void	addPhPhScattering (BasePhScatteringMatrix &matrix, Context &context, std::vector< VectorBTE > &inPopulations, std::vector< VectorBTE > &outPopulations, std::vector< std::tuple< std::vector< int >, int >> qPairIterator, Eigen::MatrixXd &innerBose, Eigen::MatrixXd &outerBose, BaseBandStructure &innerBandStructure, BaseBandStructure &outerBandStructure, PhononH0 &phononH0, Interaction3Ph &coupling3Ph, std::shared_ptr< VectorBTE > linewidth)

void	addIsotopeScattering (BasePhScatteringMatrix &matrix, Context &context, std::vector< VectorBTE > &inPopulations, std::vector< VectorBTE > &outPopulations, std::vector< std::tuple< std::vector< int >, int >> qPairIterator, Eigen::MatrixXd &innerBose, Eigen::MatrixXd &outerBose, BaseBandStructure &innerBandStructure, BaseBandStructure &outerBandStructure, std::shared_ptr< VectorBTE > linewidth)

void	addPhElScattering (BasePhScatteringMatrix &matrix, Context &context, std::vector< VectorBTE > &inPopulations, std::vector< VectorBTE > &outPopulations, BaseBandStructure &phBandStructure, BaseBandStructure &elBandStructure, StatisticsSweep &statisticsSweep, InteractionElPhWan &couplingElPhWan, std::shared_ptr< VectorBTE > linewidth)

Additional Inherited Members
Static Public Member Functions inherited from ScatteringMatrix
static void	symmetrizeCoupling (Eigen::Tensor< double, 3 > &coupling, const Eigen::VectorXd &energies1, const Eigen::VectorXd &energies2, const Eigen::VectorXd &energies3)
	Average the coupling for degenerate states. More...

Detailed Description

This class contains the logic to compute the phonon scattering matrix. The parent class ScatteringMatrix instead contains the logic for managing the operations with phonon distribution vectors.

Constructor & Destructor Documentation

◆ PhScatteringMatrix()

PhScatteringMatrix::PhScatteringMatrix	(	Context &	context_,
		StatisticsSweep &	statisticsSweep_,
		BaseBandStructure &	innerBandStructure_,
		BaseBandStructure &	outerBandStructure_,
		PhononH0 *	phononH0_ = `nullptr`
	)

Parameters

context	the user-initialized variables.
statisticsSweep	the object containing the information on the temperatures to be used in the calculation.
innerBandStructure	this is the band structure object used for integrating the sum over q2 wavevectors.
outerBandStructure	this is the bandStructure object used for integrating the sum over q1 wavevectors.
h0	the object used for constructing phonon energies.

Note: inner and outer band structures may be different, for example, if we want to compute the phonon linewidths on a path, the outer band structure contains the phonon dispersion relation along high symmetry lines, whereas the inner band structure contains the dispersion relation on a full grid of wavevectors. For transport calculations instead, inner=outer. Especially in the case of computing linewidths on a path, it might be necessary to compute phonon energies on a wavevector q3=q1+q2: for this reason, we need to pass also the phonon h0 object.

Member Function Documentation

◆ builder()

void PhScatteringMatrix::builder	(	std::shared_ptr< VectorBTE >	linewidth,
		std::vector< VectorBTE > &	inPopulations,
		std::vector< VectorBTE > &	outPopulations
	)

overrideprotectedvirtual

Pure virtual function: needs an implementation in every subclass.

Implements ScatteringMatrix.

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Friends And Related Function Documentation

◆ addPhPhScattering

void addPhPhScattering	(	BasePhScatteringMatrix &	matrix,
		Context &	context,
		std::vector< VectorBTE > &	inPopulations,
		std::vector< VectorBTE > &	outPopulations,
		std::vector< std::tuple< std::vector< int >, int >>	qPairIterator,
		Eigen::MatrixXd &	innerBose,
		Eigen::MatrixXd &	outerBose,
		BaseBandStructure &	innerBandStructure,
		BaseBandStructure &	outerBandStructure,
		PhononH0 &	phononH0,
		Interaction3Ph &	coupling3Ph,
		std::shared_ptr< VectorBTE >	linewidth
	)

friend

Very important: the code must be executed with a loop over q2 outside and a loop over q1 inside. This is because the 3-ph coupling must compute the Fourier transform on q1 and q2. The 3-ph class splits the Fourier transform in two parts, recycling the FT over q2 for more values of q1. Thus, we have some speed when executing in this order. PointHelper too assumes that order of loop execution.

Public Member Functions

Protected Member Functions

Protected Attributes

Friends