NMRWish Built-In TCL Functions
dynGetPsi: Get the protein backbone torsion angle psi N(i) CA(i) C(i) N(i+1) for selected residues.

Flag	Argument	Default	Description
`-src`			pdbSrc Source of Structure Data.
`-res`			resList\} Residue ID List.
`-chain`			cName Chain Name.
`-seg`			sName Seg Name.
`-round`			rVal Round Angles to Nearest rVal.

Notes:
Psi(i) Torsion: N(i) CA(i) C(i) N(i+1)
Return values adjusted to range -180 to 180.