Question

Dihedral angle and torsional angle are the same.

• A. True
• B. False

Answer 1

The correct option is A True

Yes, dihedral and torsional angle are exactly the same.

Dihedral angle or torsional angle is the angle between planes through two sets of three atoms, having two atoms in common.

To understand this consider the following molecule.



Here, let's try to identify 2 sets of 3 atoms where atleast 2 atoms are common. One would be $H_1-C-H_5$ and since this is a simple case, we have another $H_2-C-H_6$.

Now, if you draw a plane passing through these sets, you will get ${60}^o$ between the planes. This is the dihedral angle.

Let's take another example.

Here, the angle is made by Cl-C-Cl, where the C is represented as the dot in the middle.


Here, ${180}^o$ is the dihedral angle.