Preferences, Constants Tab
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Dialog Box Tab - called from: Settings Menu

See also Preferences - Operation Tab.

Increment for drawing circles (degrees). Arcs of circles are drawn with line segments at specified angular increments (full circles are drawn with system routines). Ellipses are also drawn with proportionate line segments, although the increments are variable. The default circle increment of 12.0 degrees has been found to give satisfactory results for laser and pen-plotting, provided atoms are not too large. Making the increment smaller may improve the appearance, at a penalty in plotting time, especially if your computer has no math coprocessor or you are using lines of finite width.

On-screen rotation increment (degrees). This is the amount by which the image is rotated in the Dialog Bar - Left. This is the value which exists when ATOMS is started; this value and not the latest value in the dialog bar itself is saved on quitting ATOMS.

On-screen displacement increment (Angstroms). This is the default amount by which a structure fragment is translated in the Dialog Bar - Fragments (Display menu). This is the value which is in the dialog when it is first called; this value and not the latest value in the dialog itself is saved on quitting ATOMS.

On-screen rescaling factor (%). This is the default amount by which the drawing is rescaled with the Scale button in the Dialog Bar - Right (Display menu). This is the value which is in the dialog when it is first called; this value and not the latest value in the dialog itself is saved on quitting ATOMS.

Default radius for atom location (Angstroms). When identifying atoms with the cursor, the given atomic radius is used for deciding when the mouse is clicked "on" an atom. However, if the input radius is zero or negative (denoting either polyhedral atoms or wire-frame atoms), this default radius is used instead.

Factor for scaling to screen or frame. In either the Maximize or Universal scaling modes (Scaling dialog, Input2 menu), the image is scaled to almost fill the screen or frame. This factor specifies how close the image comes to the edges. This scaling is not precise when Perspective projection is used, so a relatively smaller factor may be necessary if the perspective distance is small.

Dash length and dash ratio. The dashes are used for back edges of crystals (Crystal Edges and Faces) and in display of Crystal Axes and Unit Cell. Length or repeat distance is in inches/centimeters, and the length factor is the actual length of the solid part divided by the repeat distance. Note that when using Frames in output the dash length remains the same - it may be desirable to decrease the length for very small plots.

Atomic radii. One or the other of the two files, ELEMENTS.ION,ionic radii, or ELEMENTS.COV, covalent radii, is used during input of Import files and input of atomic parameters through the Input Atoms dialog (see ELEMENTS files). The Factor multiplies the full radius values during this input. Values of around 0.5 are appropriate for ball-and-stick display, while values well over 1.0 may be required for interpenetration (space-filling).

Scaling units. This sets either inches or centimeters as the units for overall use in ATOMS. This choice may be locally overridden for printing or other output by the Units setting in some of the dialogs involved.