Import SHELX.INS File
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Import SHELX.INS-93 File [ File menu (Startup) or File menu (Graphics)]

See the Import File dialog for general aspects of importing atomic-structure data files.

ATOMS is programmed only for SHELX-93 files, although it may also be possible to read SHELX-76 files.

Atom type numbers from. The Type labels radio button will use the SHELX SFAC (scattering factor) number which is the number which follows the atomic label and preceeds the atomic coordinates in the SHELX file. The numbers correlate with elements through the SFAC instruction, which must be in the SHELX file. These elements will be used to determine the atomic radii and colors using the ELEMENTS files supplied with ATOMS (which can be modified by the user). The SHELX atomic radii are not used; if an element is not in the current ELEMENTS file, the correct radius will not be supplied.

Symmetry. The Custom point or space group option will be used. Typically the true symbol can be recovered from the title. ATOMS will read the SYMM lines in the SHELX file only if they are in standard International Tables format - the translational part must precede the positional part (i.e. 1/2+x, not x+1/2). If the symmetry was copied from the Tables, there should be no problem. You can edit the symmetry operators after they are read in with the Symmetry command in the Input1 menu.

Multiple occupancy of sites. If there is an EXYZ instruction, ATOMS will use only the first atom - all others will be deleted.

FRAG instruction. Atoms listed between this instruction and the FEND instruction will be ignored.

RESI instruction. Atoms listed after this instruction will be included, but not treated in any special way.

Hydrogen atoms. SHELX has several sophisticated ways of locating hydrogen atoms which are not duplicated by ATOMS. Frequently, the positions of the hydrogen atoms are not in the.INS file, and must be taken from the output. There are several ways to do this. First, the output lines giving the hydrogen positions can be copied into the.INS file. If this is done, a type or SFAC number must be inserted after the label and before the coordinates. The hydrogen lines can also be put into a separate file and read in with the SHELX +filename include-file instruction. Second, the hydrogen lines can be put into a file of their own and read in with the input-file provision of the Input Atoms dialog in the Input1 menu, after the SHELX.INS file has been imported. Since the label and coordinates are in the default order, no modification is necessary, and a FIELDS line is not needed - only the lines with the labels and coordinates (any other fields following on the same line will be ignored). If you do this, do not check the Generate bonds box. You can generate bonds after the SHELX and the hydrogen input files have been read in, with the Bonds dialog in the Input1 menu.

Most of the instructions in a SHELX file will be ignored. However, ATOMS may not know all the current instructions. If it cannot identify an instruction, it tries to read the line as an atom line (this is the way SHELX works). If this fails, you are asked if you want to add the first four letters of the line to the list of instructions to be ignored. These instructions-to-be-ignored are at the end of the setup or Preferences file, separated by spaces and preceeded by the number of instructions. You can edit this list if necessary.

You should scan the atom list (Input Atoms dialog in the Input1 menu) to be sure nothing has been included by mistake.