4.23. FC: Calculated structure factors

Authors: Syd Hall, Jim Stewart, Richard Alden & Jim Holden

Contact: Syd Hall,Crystallography Centre, University of Western Australia, Nedlands 6907, Australia

FC calculates structure factors when refinement of atomic parameters is not required.

4.23.1. Calculation Performed

The asymmetric set of atomic sites is entered from the input archive bdf, and is used to generate symmetrically related sites for all atoms in the unit cell. The structure factor calculation is applied to these sites. The coordinates of all sites in a cell may be listed by entering the line "reset psta 4" prior to the FC line.

Overall isotropic, individual isotropic, individual anisotropic, or mixed individual thermal displacement parameters may be applied in FC. Dispersion factors and isotropic extinction corrections may also be applied provided prerequisite data is present on the input bdf.

If requested FC will calculate, and store on the bdf, the Sim (1960) weight.

w(Sim) = I1(f) / I0(f) where f = 2 FoFc/ f2

4.23.2. File Assignments

4.23.3. Example

FC disp list 7.5
scale 1.013

In this example, structure factors are calculated using all atoms in the bdf. Dispersion corrections will be applied. All reflections for which F(rel) and F(cal) differ by more than 7.5 will be listed. In addition, for this calculation, the F relative scale factor is to be set to 1.013 for scale group 1. When the updated bdf is written it will include F(cal), the estimated phase and the contributions to A and B from dispersion.

4.23.4. References