If you modify any data or setup file, be sure never to use tabs.
Data Files. The files written for each structure are of the standard ASCII type. Direct modification of these files is no longer recommended. However, occasion may arise for repairing a damaged file, which can be done with any word- or text-processor or other program which handles ASCII files.
SCRPTR Setup File. There are now only two types of data in the SCRPTR file which should be modified; the dot-patterns and the SHELX commands-to-be-ignored. The contents of this file and the DEFAULTS file are now in a user- and platform-specific setup or Preferences file
There are two sets of 32 dot-patterns (fine and coarse), each consisting of 32 lines of 8 numbers each. Each number can range from 0 to 255, with a binary 1 bit representing a black dot and 0 representing white (or color in the case of 4-bit raster files). Note that earlier versions of ATOMS may have had either 14 (V1.0) or 16 patterns in each series. The fine series, which is first, contains duplicate lines so that there are only 16 patterns for shading, even if the number of shading zones is greater than 16. These patterns could be modified to give 32 distinct shades, although it is doubtful if this would greatly improve the quality of the image.
Patterns can also be modified to give striations, hachures or other patterns for distinguishing unshaded atoms. For example, the sequence "1 1 1 1 1 1 1 1" will give vertical striations, and the sequence "255 0 0 0 0 0 0 0" will give horizontal striations. Such patterns should not be used when shading is in effect. ATOMS now has the ability to show macrosopic hachure patterns on polyhedra and atoms, so pixel-scale patterns are probably unnecessary.
The patterns in the SCRPTR file are only used for raster-file output, and for standard printer output (when ATOMS patterns are selected in Windows); they are not used for the screen.
At the end of the SCRPTR file is a list SHELX commands of four (or fewer) characters each, which are to be ignored by ATOMS when importing SHELX files. The list has ten commands per line, and is preceeded by the number of commands. If you add commands, be sure to change the number.
Although the data for the two 16-color palettes is also in the SCRPTR file, it is easiest to modify palettes with the Main Palette and Conversion Palette dialogs in the Settings menu, or to prepare files to be read in with these dialogs.
ELEMENTS files. These files, ELEMENTS.ION and ELEMENTS.COV supply default types (atomic numbers by default), radii and colors for input atoms read in from an ASCII file. See the next section for information on modification.
SCATFAC.DAT file. This file contains scattering factor data for powder and precession diffraction. The data are by default those for neutral atoms from the International Tables for X-Ray Crystallography (1974, Vol. 4). The ATOMS type numbers of input atoms are keyed to the entries in this table in order of the entries (not by element name). Other values using the same exponential form, for example different valence states, may be substituted. The coefficients are separated by blank spaces and are not confined to particular columns.
The first nine coefficients in each line are the X-ray scattering factor coefficients and the last number is the neutron scattering factor or length.
By default, number 99 in this file is used for deuterium (symbol "D") and number 98 is tritium (symbol "T"). These differ from hydrogen only in the neutron scattering factor.
The atomic type numbers, modulo 100, are used as indices to this table. For example 6, 106, 206 etc will all reference the sixth entry (carbon). Thus entries beyond 100 will be ignored. Any special or temporary entries should generally be placed in numbers 93 to 97.
If you modify any data or setup file, be sure never to use tabs.