Problems of Pseudo Symmetry

Direct-method Treatment of Phase Ambiguities due to Pseudo symmetry



        Pseudo symmetry is due to part of the structure having a higher symmetry than that of the whole structure. Phase ambiguities often occur in solving this kind of structures. Direct methods have been introduced to deal with this problem.
        There are two kinds of pseudo symmetry, i.e. enantiomorphous and translational pseudo symmetries. Direct-method treatment of the former led further to breaking phase ambiguities in protein crystallography , while that of the latter led further to ab initio determination of incommensurate modulated and composite structures.