Atom Labels
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Dialog Box - called from: Display Menu

You can show either labels or generated atom numbers. The labels will use the atomic labels entered in the Revise Atom dialog, up to 6 characters. You can specify fewer characters with the Max. letters item. The labels will be stripped of trailing blanks and centered on the projection of the atomic center, unless the Offsets are non-zero.

If the Scale box is checked, in printed output or output to a file, the labels in that output will be scaled to approximately the same relation to the drawing itself as on the screen. This is a very approximate process, and trial-and-error adjustment may still be necessary to get the desired label sizes in output. The option applies to all types of lettering on the plot, not just atom labels.

If the Background is opaque, each letter will lie on a small block of the designated color; this usually makes the labels easier to read. Other programs which read ATOMS output files may not be able to reproduce these opaque blocks in Metafile or PICT files output. Labels are not supported for Pen Plot output.

Sequence. The labels may be plotted immediately after each atom, or all at once after all atoms have been plotted. The first usually looks better, but some labels will usually be partly or completely obscured.

Use PostScript font. This allows you to enter a character string for PostScript fonts supported by a PostScript printer if such fonts do not appear in the standard system font dialog called up by the Font button. This character string usually specifies the weight (normal, bold) and slant (italic, oblique) of the font, but not the size, which is specified in the Font dialog. Certain PostScript typefaces are standard, and should be present on most PostScript printers.

The label positions are correct for stereopairs, and labels for central atoms of polyhedra will appear suspended in the interior of the polyhedra.

Show symmetry number (roman). If this box is checked, each atom label will have a superscript, in roman numerals, giving the number of the symmetry operation which generated the atom, or in the case of atoms in special positions the first operation generating that atom. This is the method for designating symmetry operations (or equivalent positions) mandated by Acta Crystallographica. The symmetry operations or positions in "xyz" form (as given in the International Tables) can be listed out with the Listings/Input option in File menu. The symmetry numbers in roman and arabic numerals for generated atoms can also be listed with the Listings/Generated Atoms option in the File menu, and in the Calculation Output option in the Input2 menu. Note that no superscript will be given to atoms generated by the first symmetry operation (x, y, z or identity), and roman numeral "i" will be given to atoms generated by the second operation, and so on.

The order of space-group symmetry operators may be changed to some extent, giving different symmetry numbers and roman superscripts. To do this, switch to the Custom symmetry option and rearrange the list of operations. The list of operations can also be edited in the saved .str file with a word processor. Operations will always be listed in groups, related by a center of inversion, and by Bravais lattice centerings.

With Atoms to omit, you can elect to omit labels for certain classes of atoms, such as non-plotting atoms (those in incomplete polyhedra, or deleted by the user) which are deleted by default.

Individual generated atoms can be omitted or deleted, by clicking on the atom and unchecking the Labels checkbox in the Generated Atom Data dialog. This type of deletion is like deleting atoms themselves (see Deleting Atoms) - when you save a file, a list is made of the generated atoms for which labels are deleted. Labels which have been deleted in this way can all be restored with the Restore All button in this dialog. Also, you can delete all labels with the Delete All button, then restore selected atoms individually with the Generated Atom Data dialog. Starting with V4.0, the lists of deleted atoms and labels use a code containing the unit-cell, the symmetry operator etc., rather than an arbitrary sequence number, so that changing the boundary conditions will not usually make the list invalid (although some deleted atoms or labels may no longer be within the boundaries). However, changing the symmetry will make the list invalid.

Labels on individual atoms can be moved onscreen with a special cursor mode controlled by the Move Labels button in the Dialog Bar - Right. The Zero Displacements button in this dialog will remove the displacements on all atom labels.

Use the color options in this dialog, not the color options in the Font dialog to set the color of the letters. Letters are always solid black in black-and-white display or output. See Input Colors/Patterns/Pens for general aspects of color input.

Note that in 3D Drawing mode the labels have an absolute position in space, including the x (front-back) coordinate. They are arbitrarily plotted a short distance in front of each atom if the after each sequence is selected. If the after all sequence is selected, they are drawn in a single plane in front of all atoms.