# Dihedral Angle

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Related to Torsion angle: Ramachandran plot

## dihedral angle

[dī′hē·drəl ‚aŋ·gəl]
(mathematics)
The angle between two planes; it is said to be zero if the planes are parallel; if the planes intersect, it is the plane angle between two lines, one in each of the planes, which pass through a point on the line of intersection of the two planes and are perpendicular to it.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Dihedral Angle

a figure formed in space by two half-planes emanating from a single straight line and also the portion of space bounded by these half-planes (see Figure 1).

Figure 1.

The half-planes are called the faces of the dihedral angle and their common straight line the edge. The dihedral angle is measured by the linear angle, that is, the angle α between two perpendiculars to the edge that emanate from one point and that lie in the different faces or, in other words, the angle formed by the intersection of the dihedral angle and a plane perpendicular to the edge.

References in periodicals archive ?
The C20-O4-C24-C25 torsion angle is 140.934 (665)o, indicating that the C24 position is S-form, which is different from 3.
Caption: Figure 9: Relationship between torsion angle and dynamic pressure.
Subsequently, the maximum stress, the wingtip displacement, and torsion angle are calculated by nonlinear static aeroelastic analysis.
O=C hydrogen contact in azole 7-lysine adduct (adducts 7LysB and 7LysP) can be characterized by comparable values of the bond length, torsion angle, and coupling constant for hydrogen bond acceptor-donor (ca 5 Hz), as well as electron density [rho] (Table 2).
37 patients were divided into 2 sternal torsion angle groups: the mild group (n = 17), in which the sternal torsion angle was less than 25[degrees]; the sever group (n = 20), in which the sternal torsion angle was equal to or more than 25[degrees].
(2) In current 3D-CT FA measurement, the projection of FA on the axial plane is measured, giving the aforementioned torsion angle. We have demonstrated that the torsion angle is larger than the actual degree of FA in theory.(3) Although in order to reduce radiation exposure, the CT scanning range is divided into two parts, femoral head part and distal femur part, compared with zero-radiation MR, CT examination will inevitably subject child patients to more radiation damage.
We focus on the torsion angle D1 and dihedral angles D2 (transferred into DD1 and DD2 for PESs depicted in Figure 2) and also present the following regular form of kinetic operators explained in Scheme 1, with
The energy, E, was calculated after a constrained geometry optimization as a function of the torsion angle, ?, at the B3LYP/6-3JG* level of theory.

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