XLAT - a microcomputer program for the refinement of cell constants. ==================================================================== B.Rupp Scripta Metallurgica 22, 1 (1988) ----------- Input files ----------- The input filename [filename.GIT] should be any name allowed by DOS or VMS and must have the filename extension .GIT Example: TEST1.GIT , C:\xlat\YBACU.GIT ------------ Input format ------------ The program reads the input file containing a minimum of control parameters and the reflection data (the XUTIL utility program can be used for creating an input file interactively). The input is consistently in free format enabling comfortable entering of data. For any item in an input line an integer code number or a zero (0) must be entered. The following input lines have to be entered in input file [filename].GIT: -------------------------------- Line 1 Title, i.e. any text -------------------------------- Example YBa2Cu3O7 Stoe PSD Ge Standard ------ Line 2 6 control code integers and one optional cell constant ------ of a non default standard 1 system 1 cubic 2 tetragonal 3 hexagonal 4 orthorhombic 2 device 0 Debye Scherrer camera 57 mm 1 Debye Scherrer camera 114 mm 2 Guinier geometry 114 mm, int.standard 3 Powder diffractometer 4 1 or 3 with (internal) standard 3 order of fitting polynom for standard regression, must be less than number of standard lines (1-3 is usually suitable) 4 type of standard material used 0 Germanium 5.657906 A 1 Silicon 5.431065 A 2 Tungsten 3.16480 A 3 any other material, ao must be provided as item 7 in this input line 5 number of standard lines to be entered, default max. 30 6 drift code for applied drift correction 0 angle dependend drift correction 1 no angular dependence of drift function 2 no drift correction applied at all 7 optional cell constant for standard material, must only be entered if code number 4 (type) equals 3 Example option 1 : 4 4 2 0 5 2 option 2 : 2 4 2 3 5 2 6.78987 ------ Line 3 3 real numbers in free format or, optional wavelength ------ symbol and 2 real numbers in F5.2 format 1 either wavelength in Angstr or wavelength symbol: CUA1 means copper K alpha 1 radiation, CO means cobalt K alpha radiation. The input is not case sensitive, aga1 would be valid, too. See Appendix A.1 and XUTIL for further the symbols. 2 film shrinkage, in mm (used only for Debye Scherrer) 3 limit of error |theta(obs)-theta(calc)|. Reflections exceeding this limit are omitted in the following refinement cycles. Example option 1 : 1.54056 0.0 0.04 option 2 : Coa1 0.00 0.03 <- note the F5.2 format ------- Lines 4 standard lines, as many as stated in line 2, column 5, ------- max. 30 in 1*theta for device 0 2*theta for device 1,3,4 4*theta for devive 2 in the sequence h, k, l, theta, in each line Example 1 1 1 31.737 ------- lines 5 up to 150 reflexions in same format as standard lines. ------- Example 1 1 1 23.76 ( 2 0 6 81.933 would be correct as well). For an example of a complete input file see the listing of TEST1.GIT in Appendix A.1. -------------- Batch commands -------------- The batch command files are required to execute the program, to assign proper names to the input/output files and to combine various files to a complete output listing. The format is always XL [filename], i.e. XL TEST3 in the PC or @XL TEST3 on VAXens. ---- NOTE ---- The file name extension .GIT is obligatory for input files in the XLAT system and therefore you should not enter it in the command line. XL [filename] executes an input file named [filename.GIT], the extension .GIT must not be entered. The output file is saved as [filename.OUT]. Example XL TEST1 ------------ Output files ------------ Output filename [filename.OUT]; the file has the same filen root as assigned to the input file. Example TEST1.GIT results in TEST1.OUT A typical output file is produced running the refinement program with TEST1.GIT as an input file (XL TEST1). The output is self explaining, further information concerning the physical meaning of the 'drift' can be found in chapter 4.1, Description of method and chapter 4.2, Practical hints. Part one of the output consists of a line printer plot of the standard's polynomial correction fit. The purpose is mainly to confirm the quality of the standard data and to check whether the choosen polynomial regression presents a reasonable fit. The graph is followed by part 2, i.e. the tabular output of the theta values and the numeric result of the cell constants refinement. Part 3 shows a graphical presentation of the individual deviations of a reflection from each of the refined cell parameters. This is in particular of interest for noncubic systems, when a reflection has a fairly well overall precision as reflected by the delta theta values in the tabular output, but obscures the fit of one particular cell constant much more than the fit of the other cell parameter(s).