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x [2009/08/06 14:41] – created clarex [2022/11/03 15:08] (current) – external edit 127.0.0.1
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 +====== 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.