Direction integrated and powder spectra:

The script make_TDS_DispersionIntensityCurvesIntegrated calculates IXS and INS scattering intensities integrated over a given axis or sphere. For a given Q, it considers a whole set of points obtained from this q by rotation operations.

It requires that you have previously done the following operations :

• symmetrisation
• Fourier transform
• Debye waller calculation for the temperature of choice

• The usage is

  make_TDS_DispersionIntensityCurvesIntegrated castep_filename input_filename  
  

  the file castep_filename can be either the name of the original castep output our the associated hdf5 file. In any case the associated hdf5 file must exist already ( make_TDS_Simmetrization must be runned beforehand )

• The input_file must set the variables :

  • Mandatories

    • APPLYTIMEREVERSAL

    • redStarts

    • redEnds

    • Nqlines

    • Nfour_interp

    • Temperature

    • resolutionfile

    • Saturation

    • lowerLimit

    • bottom_meV

    • axis

      this is the axis around which rotations are done when sphereintegral==0

    • Nangular

      this is the number of azimuthal steps

    • sphereintegral

  • if sphereintegral==1

    • Nangular2

      this is the number of polar steps

  • If NEUTRONCALC==0 ( default )

    • Lambda

  • If NEUTRONCALC==1

    • CohB
    • NeutronE

  • Optional

    • branchWeight
    • Eigscal
    • UniqueIon

EXTRA OUTPUT

• File summedoverQs.dat

  contains two columns : energy , intensity. Obtained after summing over Qs

• File alongtheline_TDS.dat :

  energy integrated intensity (TDS) for each q-value

The input variables are documented with docstrings below

noindex:

make_TDS_DispersionIntensityCurvesIntegrated.APPLYTIMEREVERSAL = 1

this is one by default. Must be coherent with previous steps

make_TDS_DispersionIntensityCurvesIntegrated.redStarts = [[-2.0, -2.0, 0.0], [2.0, 2.0, 0.0]]

The list of Q points at which calculation is made is done of N segments. The redStarts variable contains a list of N starting points in reciprocal space reduced units. Each segment i starts at redStarts[i] and ends at redEnds[i]. Within each segment the spacing between points is the segment lenght divided by Nqlines[i]

make_TDS_DispersionIntensityCurvesIntegrated.redEnds = [[2.0, 2.0, 0.0], [2.0, 2.0, 1.0]]

see redStarts

make_TDS_DispersionIntensityCurvesIntegrated.Nqlines = [200, 100]

see redStarts

make_TDS_DispersionIntensityCurvesIntegrated.Nfour_interp = 5

The number of points in each direction of the 3D reciprocal grid. The hdf5 file must contain a previous pretreatement done with the same parameter.

make_TDS_DispersionIntensityCurvesIntegrated.Temperature = 100

The hdf5 file must include DW factors calculated ALSO at this temperature.

The temperature at which DW factors have been calculated.

Units are Kelvin

make_TDS_DispersionIntensityCurvesIntegrated.resolutionfile = ''

a two column file : first the energy in cm-1, second the value of resolution function

make_TDS_DispersionIntensityCurvesIntegrated.Lambda = 1.0

For X-ray scattering : the wavelenght in Angstroems.

make_TDS_DispersionIntensityCurvesIntegrated.Saturation = 0

To limit intensity at peaks : intensity is saturated at this value

make_TDS_DispersionIntensityCurvesIntegrated.lowerLimit = 0

To correct the dynamical range, when displaying, the intensity is clipped to prevent it going below this value

make_TDS_DispersionIntensityCurvesIntegrated.bottom_meV = 0

Calculated eigenvalues are clipped to this value before use.

make_TDS_DispersionIntensityCurvesIntegrated.NEUTRONCALC = 0

This activate neutron scattering calculations.

make_TDS_DispersionIntensityCurvesIntegrated.CohB = None

When neutroncalc is on, this must be a dictionary : for each atom name the Coherent lenght.

make_TDS_DispersionIntensityCurvesIntegrated.NeutronE = 0

When neutroncalc is on, the neutron energy in meV

make_TDS_DispersionIntensityCurvesIntegrated.branchWeight = None

a list of weights : one per branch.

make_TDS_DispersionIntensityCurvesIntegrated.Eigscal = 0

EigScal==1 Intensity are calculated WITH only eigenvector scalar products ; ==2 Intensity are calculated WITH only eigenvector scalar products PLUS Mass factor

make_TDS_DispersionIntensityCurvesIntegrated.UniqueIon = -1

If >=0. Selects one ion. All the other will be silent.

make_TDS_DispersionIntensityCurvesIntegrated.axis = [0.0, 0.0, 1.0]

Rotation axis

make_TDS_DispersionIntensityCurvesIntegrated.Nangular = 4

No of angular steps over 2pi

make_TDS_DispersionIntensityCurvesIntegrated.sphereintegral = 0

if set to 1 : the whole sphere is integrated

make_TDS_DispersionIntensityCurvesIntegrated.Nangular2 = 1

if sphereintegral == 1 this variable has to be set : Nangular for No of azimuth angle steps, Nangular2 for No of polar angle steps