SIR92 Invariants

Preparation of data for INVARIANTS routine


NRTRIPLETS n

The number of strongest reflections for the sigma2 search. Default = number computed by normalization routine.

GMIN x

Triplets with G > x are not actively used. Default value x=0.6 (in any case x > 0.2).

EMIN x

Minimum value for the normalized structure factors in the sigma2 search. Default = minimum value of E for the strongest reflections selected by normalization routine.

NRPSIZERO n

The number of weakest reflections for the psi-zero search. Default = number computed by normalization routine.

EMAX x

Maximum value of E for the weak reflections for the psi-zero search (up to a maximum of NRPSIZERO reflections).

COCHRAN

To use the p-3 formula. (By default p-10 formula is used).

NUMK n

The number of free-vectors used by p-10. Default value is provided by SIR92 according to the structural complexity:

                        n = min ( natom/msym + 30, 70 )
where natom is the number of atoms in the cell and msym is the number of symmetry operators of the space group.

CORRECTION x

If a pseudotranslation procedure is on, a correction factor depending on x is applied to the probabilistic argument of weak-weak-weak triplets when they are present. The default value is calculated by the program.

           x = -1 eliminates weak-weak-weak triplets,
           x =  1 corresponds to the largest confidence in them.

BIG n

This keyword is used to modify the number of triplets to estimate. If n is omitted, up to 20000 triplets will be estimated. (Default 8000).