File Applications/SpinW/m_files/sw_egrid.m

  creates energy for spectrum color plot
 
  spectra = SW_EGRID(spectra, 'Option1', Value1, ...) 
 
  It creates a grid along energy and stores the requested correlation
  function component(s) binned in energy using the grid.
 
  Input:
 
  spectra   Input structure, contains calculated correlation functions.
 
  Options:
 
  component Selects which correlation function component to be binned in
            energy. The possible options are:
                'Sperp' bins the magnetic neutron scattering intensity
                        (<Sperp * Sperp> expectation value).
                        Default.
                'Sab'   bins the selected components of the spin-spin
                        correlation function. Letter a and b can be 'x',
                        'y' or 'z'. For example: 'Sxx' will convolute the
                        xx component of the correlation function with the
                        dispersion. xyz is the standard coordinate system,
                        see online documentation of sw.
                'Mab'   bins the selected components of the spin-spin
                        correlation function. Letter a and b can be 'x',
                        'y' or 'z'. For example: 'Mxx' will convolute the
                        xx component of the correlation function with the
                        dispersion. The coordinates here are in the
                        Blume-Maleev coordinate system, see below.
                'Pab'   bins the selected element of the polarisation
                        matrix. Letter a and b can be 'x', 'y' or 'z'. For
                        example: 'Pyy' will convolute the yy component of
                        the polarisation matrix with the dispersion. The
                        coordinates used are in the Blume-Maleev coordinate
                        system, see below.
                'Pa'    bins the intensity of the simulated polarised
                        neutron scattering, with inciden polarisation of
                        Pa. Letter a can be 'x', 'y' or 'z'. For example:
                        'Py' will convolute the scattering intensity
                        simulated for incident polarisation Pi || y. The
                        used coordinates are in the Blume-Maleev coordinate
                        system, see below.
                'fName' where fName is one of the field names of the input
                        structure spectra. This field should contain a
                        matrix with size [nMode nHkl].
            Any linear combination of the above are allowed, for example:
            'Sxx+2*Syy' bins the linear combination of the xx component of
            the spin-spin correlation function with the yy component.
            Several cross section can be convoluted and stored
            independently, if component is a cell array containing strings
            each containing any linear combination of cross sections as
            above, the cell array needs to have size [1 nCell].
 
  Evect     Vector, defined the center of the energy bins of the calculated
            output, dimensions ar is [1 nE]. The energy units are defined
            by the unit.kB property of the sw object. Default is
            linspace(0,1.1*maxOmega,500).
  T         Temperature to calculate the Bose factor in units
            depending on the Boltzmann constant (sw.unit.kB). Default
            temperature is taken from obj.single_ion.T. The Bose factor is
            includec in swConv field of the output.
  sumtwin   If true, the spectra of the different twins will be summed
            together weighted with the normalized volume fractions. Default
            is true.
  modeIdx   Select certain spin wave modes from the 2*nMagAtom number of
            modes to include in the output. Default is 1:2*nMagAtom to
            include all modes.
 
  The Blume-Maleev coordinate system is a cartesian coordinate system
  with (xBM, yBM and zBM) basis vectors as follows:
            xBM    parallel to the momentum transfer Q,
            yBM    perpendicular to xBM in the scattering plane,
            zBM    perpendicular to the scattering plane.
 
 
  Output:
 
  spectra contains the following additional fields beside the input:
 
  swConv    Stores the selected cross section binned along energy, size is
            [nE nHkl]. Includes the Bose factor.
  swInt     Stores the selected cross sections for every mode, size is
            [nMode nHkl].
  T         Input temperature.
  component Cell that contains the input component selector strings.
  Evect     Input energy bin vector.
  param     All the other input parameters.
 
  If 'component' parameter is a cell array or the spectra of multiple
  twins are convoluted separately, swConv and swInt will be packaged into
  a cell. The dimensions of the cell are [nConv nTwin].
 
  Example:
 
  spectra = sw_egrid(spectra,'component',{'Sxx+Syy' 'Szz'},'Evect',linspace(0,5,51));
 
  The line will create an energy bin, with steps of 0.1 and bins the
  spin-spin correlation function. Two different matrices will be
  calculated, first using the sum of the Sxx and Syy components, second
  will contain the Szz component of the correlation function.
 
  See also SW.SPINWAVE, SW_NEUTRON.