[x_calculation_step !E]

Calculation step used in the generation of phase peaks and fit_obj’s. Peak_Calculation_Step is the actual step size used, it is defined is as follows:

For and x-axis with equal steps and x_calculation_step not defined then

Peak_Calculation_Step =  “Observed data step size” / convolution_step


Peak_Calculation_Step =  x_calculation_step / convolution_step

x_calculation_step can be a function of Xo and Th. In some situations it may be computationally efficient to write x_calculation_step in terms of the function Yobs_dx_at and the reserved parameter Xo. It is also mandatory to define x_calculation_step for data with unequal x-axis steps (*.xy or *.xye data files). Example uses of x_calculation_step is as follows:

x_calculation_step .01

x_calculation_step = .02 (1 + Tan(Th));

x_calculation_step = Yobs_dx_at(Xo);

[xdd $file [{ $data }] [range #] [xye_format] [gsas_format] [fullprof_format] ]…

Defines the start of xdd dependent keywords and the file containing the observed data.

{$data} allow for insertion of ASCII data directly into the INP file.

range applies to Bruker AXS *.RAW data files; in multi-range files it defines the range to be refined with the first range starting at 1. range is set to 1 by default.

xye_format (see section 10 as well) signals the loading of columns of x, y and error values; additional columns are ignored. gsas_format and fullprof_format signals the loading of GSAS and FullProf file formats.

The following instruction will refine on the first range in the data file pbso4.raw:

xdd pbso4.raw

To following will refine on the third range:

xdd pbso4.raw range 3

To read data directly from an INP file, the following can be used:

xdd {

1 1 10  ' start, step and finish (equidistant data)

1 2 3 4 5 6 7 8 9 10



xdd {

_xy ' switch indicating x-y format

0.1 1   0.2 2   …


[xdd_out $file [append] ]…

Used for writing xdd dependent details to file. The out_eqn can contain the reserved parameter names of X, Yobs, Ycalc and SigmaYobs. See the keyword out for a description of out_record. The Out_Yobs_Ycalc_and_Difference macro is a good example of using xdd_out.

[xdd_scr  $file] …





[auto_scale !E] 

[i_on_error_ratio_tolerance #]

[num_highest_I_values_to_keep #num]

xdd_scrdefines single crystal data from the file $file. The file can have extensions of *.HKL for ShelX HKL4 format or *.SCR for SCR format. All xdd and str keywords that are not dependent on powder data can be used by xdd_scr and hkl_Is_from_hkl4. Single crystal data is internally stored in 2q versus Fo2 format. This means that a lam definition is necessary and the keywords start_X, finish_X and exclude can be used with xdd_scr.

dont_merge_equivalent_reflections unmerges equivalent reflections, see also section 7.3.3.

dont_merge_Friedel_pairs prevents the merging of Friedel pairs.

ignore_differences_in_Friedel_pairs forces the use of Eq. (7‑12) for calculating F2.

auto_scale rewrites  the scale parameter in terms of F2. This eliminates the need for the scale parameter. The value determined for auto_scale is updated at the end of refinement.

i_on_error_ratio_tolerance filters out hkl’s that does not meet the condition:

|Fo|  >   i_on_error_ratio_tolerance |Sigma(Fo)|

num_highest_I_values_to_keep removes all hkl’s except for #num hkl’s with the highest Fo values.

An example input segment for single crystal data refinement is as follows:

xdd_scr ylidm.hkl


finish_X 35

weighting = 1 / (Sin(X Deg / 2) Max(1, Yobs));


   a  5.9636

   b  9.0390

   c 18.3955

   scale @ 1.6039731906

   i_on_error_ratio_tolerance 4

   site S1  x @ 0.8090  y @ 0.1805  z @ 0.7402  occ S 1  beq 2

   site O1  x @ 0.0901  y @ 0.8151  z @ 0.2234  occ O 1  beq 2


The SCR format is white space delimited and consists of entries of h, k, l, m, d, 2q, Fo2 which is the format outputted by the Create_hklm_d_Th2_Ip_file macro.


[xoI E]…

Defines a phase type that uses x-axis space for generating peak positions, see example XOIS.INP. xo corresponds to the peak position and I is the intensity parameter before applying any scale_pks equations.

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