-torsion <axis> <θ>
This option allows to apply torsion to the system around a cartesian axis.
The user has to provide the axis of rotation (has to be x, y or z -referring to cartesian axes), and the angle of rotation θ (in degrees).
The axis of rotation is the center of the plane normal to the <axis>. If you want to rotate the system around another point of your system, you can use the option -shift.
If forces (fx,fy,fz) or velocities (vx,vy,vz) exist as auxiliary properties, then they are rotated accordingly.
If a selection was defined (with the option -select) then the rotation is applied only to selected atoms, and the box is not rotated. This can result in some atoms being out of the box, which can be fixed thanks to the option -wrap.
This option does not change the dimensions of the cell, nor the elastic tensor if it is defined.
By default no torsion is applied.
atomsk initial.cfg -torsion x 10 final.xyz
This will apply a torsion of 10 degrees around X.