The '.hkl' Reflection Data File

THE REFLECTION DATA FILE 'name.hkl'

The '.hkl' file consists of one line per reflection in FORMAT(3I4,2F8.2,I4) for h,k,l,Fo2,sigma(Fo2), and batch number. This file should be terminated by a record with all items zero; individual data sets within the file should NOT be separated from one another - the batch numbers serve to distinguish between groups of reflections for which separate scale factors are to be refined (see the BASF instruction). The reflection order and the batch number order is unimportant. This '.hkl' file is read each time the program is run; unlike SHELX-76, there is no facility for intermediate storage of binary data. This enhances computer independence and eliminates several possible sources of confusion. The '.hkl' file is read after the HKLF instruction (which terminates the '.ins' file) has been interpreted. The HKLF instruction specifies the format of the '.hkl' file, and allows scale factors and a reorientation matrix to be applied. For further details see the specification of the HKLF instruction.

Lorentz, polarization and absorption corrections are assumed to have been applied to the data in the '.hkl' file. If SHELXA is used for the absorption corrections, it will have read a file name.raw (containing direction cosines) and written 'name.hkl' (without cosines). Since SHELXA can read a SHELXL-93 '.ins' file, empirical absorption corrections (which require SHELXA to calculate Fc2) may be applied more than once to the original data in the course of a structure determination simply by running SHELXA immediately before SHELXL-93 with the same '.ins' file. Note that there are special extensions to the '.hkl' format for Laue and powder data, as well as for twinned crystals which cannot be handled by a TWIN instruction alone.

In general the '.hkl' file should contain all measured reflections without rejection of systematic absences or merging of equivalents. The systematic absences and R(int) for equivalents provide an excellent check on the space group assignment and consistency of the input data. Since complex scattering factors are used throughout by SHELXL-93 it is important NOT to average Friedel opposites in preparing this file.

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