Abillon E
Biophys Struct Mech. 1982;8(4):257-70. doi: 10.1007/BF00537205.
The geometrical relations between the 15 typical parameters (bond lengths and angles, torsion angles) of a five-membered ring are derived for any ring then for a regular one. It is demonstrated that for the case of the 20 symmetrical C2 and CS conformations, only geometrical considerations are needed to obtain the pseudorotation formulae for the torsion angles. However, the puckering intensity as well as the bond angle values cannot be expressed from geometrical constraints alone but would require energetical considerations.
首先推导五元环15个典型参数（键长、键角、扭转角）之间的几何关系，先是针对任意环，然后是针对正则环。结果表明，对于20种对称的C2和CS构象的情况，仅需几何考量就能得出扭转角的假旋转公式。然而，褶皱强度以及键角值不能仅由几何约束来表示，而是需要能量方面的考量。
