Import CCDC FDAT File
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Import CCDC FDAT File [ File menu (Startup) or File menu (Graphics)]

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

Most of the FDAT files have a "connection table" which specifies the bonds defining a single molecule, while the unit-cell may contain several molecules. Thus the radio buttons give you a choice of importing the file as a crystal or as a molecule.

When imported as a molecule, the structure will use the No Boundaries (Molecule) boundary option, and no symmetry. The files normally contain a unique set of input atoms, which are the same as those required for input of a crystal in ATOMS, plus in many cases some extra symmetry-derived atoms necessary to complete the molecule; all these atoms are used as input atoms when importing as a molecule. With the Atomic radii radio buttons, you can choose to use either the radius values in the CCDC files, or those in the ELEMENTS file; in any case, the type number (atomic number), colors and patterns will be obtained from the ELEMENTS file using the elemental symbol which is in the first one or two characters of the FDAT atom. The radius values in the CCDC files typically are covalent radii, slightly smaller than those required for contact of bonded atoms. For a space-filling or interpenetrating atoms model, they may need to be increased, and for a ball-and-stick model they may need to be decreased. The radii of all atoms can be changed by a factor with the Atoms - Global dialog in the Input1 menu. All bonds between atoms will be the same; the radius, colors and patterns can be defined with the Define Bonds for Molecule button; this will call up a dialog which is similar to that which comes up for individual bonds (Bond Data in the Input1 menu); however, atom types and distance limits are not used and are omitted from this dialog. After calculation, the radius, colors and patterns can be changed with the Bonds command in the Input1 menu. There will be only one bond type in the list.

Note that importing a CCDC FDAT file as a molecule uses a different procedure from the Locate Molecules in Crystal boundary option, which is used in most other cases when importing a crystal structure as molecules. The Locate Molecules in Crystal boundary option uses the bond and polymer specifications entered in ATOMS to isolate the molecules, whereas the FDAT files usually already contain the linkage information which defines molecules. If you wish to use the Locate Molecules in Crystal option, you must import the FDAT file as a crystal, then change the boundary option.

When imported as a crystal, the structure will use only the unique set of atoms, omitting the extra ones. The boundary option will be Default Unit Cell, current default suboption.