利用者:4dimp/下書き/ベリー擬回転
ベリー擬回転（ベリーぎかいてん、英:Beryy pseudorotation）とは、
ax = アキシアル配位子 (on unique axis)
eq = エクアトリアル配位子 (in plane perpendicular to unique axis)
The Berry mechanism, or Berry pseudorotation mechanism, is a type of vibration causing molecules of certain geometries to isomerize by exchanging the two axial ligands (see Figure at right) for two of the equatorial ones. It is the most widely accepted mechanism for pseudorotation. It most commonly occurs in trigonal bipyramidal molecules, such as PF5, though it can also occur in molecules with a square pyramidal geometry. The Berry mechanism is named after R. Stephen Berry.