6CYANA: distances stereoexpand - CYANA command

Parameters: selection=<string>             (default: <blank>)
            shrink

This command replaces in the distance restraints that match the
selection <string> the diastereotopic substitutents that are not
stereospecificly assigned by their corresponding pseudoatoms. By
default, the selection made in the most recent 'distances select'
command is used, or all distance restraints if no selection has been
made so far.

If the option 'shrink' is set, a pseudoatom correction is added to
the upper distance bound. The corrected upper distance bound u is
calculated from the original upper bound u according to the formula

  u' = (u^-6 + (u + c1)^-6 + (u + c2)^-6 + (u + c1 + c2)^-6)^(-1/6),

where c1 denotes the distance between the first diatereotopic
substituent and its corresponding pseudoatom, and c2 denotes
the distance between the second diatereotopic substituent and its
corresponding pseudoatom. If the first or the second atom involved in
the restraint are not diastereotopic substitutents, or stereospecificly
assigned, then the corresponding terms that involve c1 and c2 are
omitted from the sum in the formula for u'.
