To calculate torsion angles for 3D chemical table:

• Read in a chemical spreadsheet File/Open SDF - the sdf file needs to contain 3D coordinates.
• Choose Chemistry/Torsion Analysis
• Sketch a torsion pattern by marking four torsion atoms with labels 1-4 e.g [c:2]([c:3]:[n:4]):[n:1] Labels can be set as shown in the molecular editor below - right click on an atom and choose 'Atom Mapping Number'.

There are some options:

• Try all possible matches - if torsion pattern matches more than once in a chemical then multiple values will be return
• Take Absolute Vale - takes Abs(torsion_angle) # 180 or -180 -> 180
• Two fold symmetry - takes Min( torsion_angle, 180-torsion_angle )
• Build angle distribution histogram - a histogram will be displayed in the panel next to the table.