Files of this type are read and written by ATOMS and CRYSCON (Shape Software). Such files have atomic-coordinate information, but this is ignored by SHAPE.
All information needed for a SHAPE calculation can be entered with these files, and they should be easy to write with other software. The SPGP , HALL , SYMM AND LATT lines are used only in the Donnay-Harker Morphology option.
The required information is entered in lines which begin with one of the 4-letter keywords shown in boldface type below. Information follows the keywords in numeric or character fields - fields do not contain spaces (may contain underscores), and are separated from each other by spaces.
TITL line. Up to 76 characters (may contain spaces).
CELL line. The unit-cell lengths in Angstroms and the interaxial angles in degrees (6 floating-point values).
SPGP line. The Hermann-Maughin or standard International symbol for the space group. There should be no spaces in the symbol, although there may be underscores (which are ignored when the symbol is interpreted).
HALL line. The Hall symbol for the space group. There should be no spaces in the symbol, although there may be underscores (which are ignored when the symbol is interpreted. If this line comes after the SPGP line (or that line is absent), the Hall symbol will be used.
SYMM lines. These give symmetry operators in "xyz" form, that is in the form in which the coordinates of the general position are listed in the International Tables for X-Ray Crystallography . Fractions must be given as integers separated by a slash ("1/2", "2/3"), rather than decimals ("0.5", "0.333"). The x, y and z positions must be separated by commas and there should be no spaces in the operator. There should be one line for each operator. If the space group is centrosymmetric, only half the operators need be given, if the origin is on a center of inversion. If the origin is not on a center, all operators must be given and the space group should be denoted non-centric in the LATT line.
LATT line. This gives the Bravais lattice type (single capital character), followed by a space and 0 if the space group is centrosymmetric or 1 if it is non-centric.
Generally, the SYMM/LATT combination supercedes SPGP or HALL lines - if SYMM lines are present, SHAPE will attempt to determine the space group from them, and if successful will replace any H-M or Hall symbols which have been read in.
FORM lines. These lines contain the three indices and the central distance for each form. The indices may be floating point for entry in the Cartesian (QSHAPE) operating mode - be sure to set this mode before reading the file.