##
7.1 Changing bond lengths, bond angles, and torsion angles

To change a bond length, a bond angle, or a torsion angle click on the corresponding atoms and then press the right mouse button. This will display the length of the bond and the value of the bond or torsion angle, respectively (cf. p. ). Now click on the number with the left mouse button. A cursor will appear and the value displayed can be changed. After pressing `Return` the new value for the bond length, bond angle, or torsion angle will be set. The atom which has been clicked on first (and all atoms connected to it) will be moved. It is impossible to change bond lengths, bond angles, or torsion angles if they are part of a ring. All changes in geometry can be reversed by using `Undo geometry change` from the `Geometry` menu or the corresponding button in the molecule editor dialog box. The number of undos is unlimited.