# CEN, center

NAME
CEN, center - change the origin of the internal coordinate system.
SYNOPSIS
CEN
center
DESCRIPTION
An internal coordinate system is assigned to each structure. The command CEN (center) redefines the position of this origin. A new origin will be equal to the geometric center position calculated for selected atoms. This may be quite useful if working with a large structure. By selecting a small portion of the structure, or even a single atom, the internal system origin may be set to a place which contains the most interesting part of the structure. Rotations, slab changes and color changes will be done with respect to new origin. This will keep the interesting part in the same part of the screen. It is recommended to hide the uninteresting part of the structure, to make rotations and other transformations faster. When you load the structure the geometric center of the whole structure is used as the internal system origin. If you displaced the origin but now you want to move it back to the original position, just execute the following commands:
sel all
cen
This command is applied to the structure which is currently hangled, i.e. the one to which the command CATCH was applied last.
NOTES
(1) The command CEN (center) does not move the structure to the screen center. To do this, use the command POS (POSITION).
RELATED COMMANDS
POS sets the origin of the internal system to the specified position in the main (global) coordinate system.