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x [2009/08/06 15:41]
clare created
x [2009/08/27 12:21] (current)
clare
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 ====== x ====== ====== x ======
  
 +**[//​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//​
 +
 +otherwise
 +
 +Peak_Calculation_Step =  //​x_calculation_step//​ / //​convolution_step//​
 +
 +//​x_calculation_step c//an 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 //​[[#​k045|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] …**
 +
 +**[//​dont_merge_equivalent_reflections//​]**
 +
 +**[//​dont_merge_Friedel_pairs//​]**
 +
 +**[//​ignore_differences_in_Friedel_pairs//​]  **
 +
 +**[//​str//​]…**
 +
 +**[//​auto_scale//​ !E] **
 +
 +**[//​i_on_error_ratio_tolerance//​ #]**
 +
 +**[//​num_highest_I_values_to_keep//​ #num]**
 +
 +//​xdd_scr//​defines 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 F<​sub>​o</​sub><​sup>​2</​sup>​ 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 F<​sup>​2</​sup>​.
 +
 +//​auto_scale//​ rewrites  the //scale// parameter in terms of F<​sup>​2</​sup>​. 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:
 +
 +%%|%%F<​sub>​o</​sub>​%%|%%  >   i_on_error_ratio_tolerance |Sigma(F<​sub>​o</​sub>​)|
 +
 +//​num_highest_I_values_to_keep r//emoves all hkl’s except for //#//num hkl’s with the highest F<​sub>​o</​sub>​ values.
 +
 +An example input segment for single crystal data refinement is as follows:
 +
 +xdd_scr ylidm.hkl
 +
 +MoKa2(0.001)
 +
 +finish_X 35
 +
 +weighting = 1 / (Sin(X Deg / 2) Max(1, Yobs));
 +
 +STR(P212121)
 +
 +   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, F<​sub>​o</​sub><​sup>​2</​sup>​ which is the format outputted by the Create_hklm_d_Th2_Ip_file macro.
 +
 +**[//​xo_Is//​]...**
 +
 +**[//xo// E  //I// 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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