Usage:
focus [ atom-spec ]

Focus adjusts the view and center of rotation based on atoms, bonds, and/or ribbon segments that are displayed (possibly including items that are invisible) If atoms are specified, only those both specified and displayed (possibly including some that are invisible) are considered in making the adjustments. Focusing consists of

1. translating to center the item(s), scaling them to fill the view, and moving the clipping planes to bracket the item(s) in the Z dimension (like the command window)
2. making the center of the bounding box of the item(s) the center of rotation (like the command cofr)

See also: center, cofr, set, setcom, window