When reading from FDAT or free-format input, several structures may be displayed on the same plot. This allows up to 10 structures to be superimposed and compared.
To show which atoms belong to which structure, the colour option COL STR is available.
The behaviour of certain functions is modified where more than one structure is displayed. In multiple structure mode, commands will apply to all structures by default. However, operations which modify the intramolecular connectivity, e.g. Intra, AddB, DelB, HCal, Geom->Centroid can only apply to the last structure read in. These commands should be applied where necessary before reading another structure. Reading in another structure resets most other attributes of the structures already read in. In particular, intermolecular contacts and the molecule list are not retained.
If one structure is selected as the current structure, some commands will only apply to the current structure, including Inter, Hbond, Sphr, Info, Exp, HOME, STDS. Other commands always operate globally, including Sol, Shad, Colr, Ster, Hydr, Cell, Post. A few commands cannot be used in multiple display mode, including Slice, ECal.
When all structures are selected, the rotation, translation and view buttons apply globally, i.e. the whole plot is rotated and/or translated.
When a single structure is selected, rotation commands rotate that structure relative to the other structures displayed. The origin of rotation is the unit cell origin of the structure in question. Similarly, the translation buttons move the selected structure relative to the other structures in the plot frame. The view buttons only change the orientation of the selected structures, the relative translations are not affected. On reset or reading in another structure, the relative translations are set to zero.
Geometric objects, i.e. planes and vectors, are the property of one structure and are transformed by rotation and translation along with the atoms of that structure. As a result, it is not possible to define a geometric object based on atoms in more than one structure.
Measurements can be performed on atoms or objects which are in different structures. The distances and angles so measured are dependent on the relative rotations and translations of the structures. Distances and angles on the plot are updated as structures are rotated and/or translated. Measurements in the distance list in the top left are not updated, the initial values when the measurement was first performed are retained.
KSTR keeps the current structure, so it is retained when the next structure is read.
CSTR n sets the current structure to n. Certain operations will only apply to structure n. CSTR 0 selects all structures.
SSTR returns to single structure display. Only the last structure read will be displayed.