Pscf::Prdc::Basis< D >::Star Class Reference

A list of wavevectors that are related by space-group symmetries. More...

#include <Basis.h>

Public Attributes
int	size
	Number of wavevectors in this star.
int	beginId
	Wave index of first wavevector in star.
int	endId
	Wave index of first wavevector of the next star.
int	invertFlag
	Index for inversion symmetry of star.
IntVec< D >	waveBz
	Integer indices indicesBz of a characteristic wave of this star.
int	starId
	Index of this star in ordered array of all stars.
int	basisId
	Index of basis function associated with this star.
bool	cancel
	Is this star cancelled, i.e., associated with a zero function?

Detailed Description

template<int D>
class Pscf::Prdc::Basis< D >::Star

A list of wavevectors that are related by space-group symmetries.

The wavevectors in a star form a continuous block within the array waves defined by the Basis classes. Within this block, waves are listed in descending lexigraphical order of their integer (ijk) indices as given by Basis::Wave::indicesBz.

Definition at line 445 of file Basis.h.

Member Data Documentation

size

template<int D>

int Pscf::Prdc::Basis< D >::Star::size

Number of wavevectors in this star.

Definition at line 453 of file Basis.h.

Referenced by pscfpp.file.File::__eq__(), pscfpp.file.File::__init__(), pscfpp.text.Record::__init__(), pscfpp.file.File::__repr__(), pscfpp.text.Record::__str__(), Pscf::Prdc::readBasisData(), and Pscf::Prdc::writeBasisData().

beginId

template<int D>

int Pscf::Prdc::Basis< D >::Star::beginId

Wave index of first wavevector in star.

Definition at line 458 of file Basis.h.

Referenced by Pscf::Prdc::readBasisData().

endId

template<int D>

int Pscf::Prdc::Basis< D >::Star::endId

Wave index of first wavevector of the next star.

This index is one past the wave index of the last wavevector of this star.

Definition at line 466 of file Basis.h.

invertFlag

template<int D>

int Pscf::Prdc::Basis< D >::Star::invertFlag

Index for inversion symmetry of star.

A star is said to be closed under inversion iff, for each vector G in the star, -G is also in the star. If a star S is not closed under inversion, then there is another star S' that is related to S by inversion, i.e., such that for each G in S, -G is in S'. Stars that are related by inversion are listed consecutively within the waves array of the Basis class.

If a star is closed under inversion, then invertFlag = 0.

If a star is not closed under inversion, then invertFlag = +1 or -1, with inverFlag = +1 for the first star in the pair of stars related by inversion and invertFlag = -1 for the second.

In a centro-symmetric group (i.e., a group that includes the inversion operation, with an inversion center at the origin of the coordinate system), all stars are closed under inversion. In this case, all stars in the basis must thus have starInvert = 0.

In a non-centro-symmetric group, a stars may either be closed closed under inversion (starInvert = 0) or belong to a pair of consecutive stars that are related by inversion (starInver = +1 or -1).

Definition at line 495 of file Basis.h.

Referenced by Pscf::Prdc::readBasisData().

waveBz

template<int D>

IntVec<D> Pscf::Prdc::Basis< D >::Star::waveBz

Integer indices indicesBz of a characteristic wave of this star.

Wave given here is the value of indicesBz for a characteristic wave for the star. For invertFlag = 0 or 1, the characteristic wave is the first wave in the star. For invertFlag = -1, this is the negation of the waveBz of the partner star for which invertFlag = 1.

The coefficient of wave waveBz is always real and positive.

Definition at line 508 of file Basis.h.

Referenced by Pscf::Prdc::readBasisData(), and Pscf::Prdc::writeBasisData().

starId

template<int D>

int Pscf::Prdc::Basis< D >::Star::starId

Index of this star in ordered array of all stars.

This is the index of this star within array stars_.

Definition at line 515 of file Basis.h.

basisId

template<int D>

int Pscf::Prdc::Basis< D >::Star::basisId

Index of basis function associated with this star.

If this star is not cancelled (cancel == false), then basisId is set equal to the index of the associated basis function in in a list of nonzero basis functions or (equivalently) in a list of non-cancelled stars.

If this star is cancelled (cancel == true), then basisId = -1.

Definition at line 527 of file Basis.h.

Referenced by Pscf::Prdc::readBasisData().

cancel

template<int D>

bool Pscf::Prdc::Basis< D >::Star::cancel

Is this star cancelled, i.e., associated with a zero function?

The cancel flag is true iff no nonzero basis function can be constructed from the waves of this star that is invariant under all elements of the space group. Basis functions are thus associated only with stars for which cancel == false.

Each cancelled star contains a set of waves that are related by symmetry for which the X-ray or neutron scattering intensity would exhibit a systematic cancellation required by the space group symmetry.

Definition at line 542 of file Basis.h.

Referenced by Pscf::Prdc::readBasisData(), and Pscf::Prdc::writeBasisData().

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

• Basis.h