Software for Diffraction

The spec software package provides a powerful environment for the operation of X-ray diffractometers. spec includes specific functionality like geometry calculations, operation modes and macro libraries for different standard geometries like fourc, sixc, kappa, twoc and various liquid surface diffractometers between others. New geometries could be added in collaboration with users.

Together with specific diffractometer functionalities spec presents the user with an optimal environment for data acquisition including experimental sequences, large choice of hardware supported, data analysis routines and data display.


The standard spec manual describes in detail the operation of diffractometers in spec, and in particular for a fourc diffractometer.

The six-circle diffractometer combines the features of a four-circle and z-axis diffractometer. spec implements calculations for the sixc geometry based on "M. Lohmeier and E. Vlieg in J.Appl.Cryst. , 26 , 706 (1993)"

The psi-circle diffractometer calculations are based on those presented in a paper by H. You of Argonne National Lab in J. Appl. Cryst. , 32 , 614-623 (1999). (See http://journals.iucr.org/j/issues/1999/04/00/hn0093 )


Specialized macros exists to work with diffractometers.

  • Setup crystal parameters and work with orientation matrix UB: setlat, setor0, setor1, reflex, showUB
  • Convert between crystal and laboratory coordinates: ca, ci, wh
  • Displace the crystal in crystallographic coordinates mr, br, cal
  • Scan along crystal axes: hklscan and its variations, radial and circle scans,
  • Work on special modes like, for example, powder diffraction mode: setpowder

See also

mr br ca hklscan sixc psic