“dihedral” shows dihedral angles formed between any four atoms.

dihedral [ name [, selection1 [, selection2 [, selection3 [, selection4 ]]]]]

“dihedral” alone will show the dihedral angle formed by selections (pk1), (pk2), (pk3), and (pk4), which can be set using the “PkAt” mouse action (typically, Ctrl-middle-click)

distance | angle | cmd.dihedral | commands