# Direction Modify

- Type
- Scope
- Projection
- View

Change here object and crystallographic data for a single direction or a list of directions.

To modify a direction, click over its graphic image, or write its identification (name and number) on the Direction entry. To modify a list of directions, press the button List (after creating the list of directions with Direction->Select). Parameters for empty entries or Local choices remain unchanged.

To change a direction name write the new name in the Direction entry, followed by the direction number (GAMGI needs the number to identify the direction). To change the name for a list of directions, press List first and then write the new common name in the Name entry.

### Reference

GAMGI can handle crystallographic directions (selecting Cell), related with a cell containing the relevant crystallographic information, and atomic directions (selecting Atoms), defined by two non-coincident atoms.

For a single direction, Reference can be Cell, Atoms or Local. For a list of directions, Reference must be Local.

When Cell or Atoms is selected, the direction is recreated from scratch (as if using Direction->Create) and its old content is removed. As this requires local information for each direction, it cannot be done for a lists of directions. When Local is selected, previous features and contents are preserved, unless when specifically changed. Cell To create crystallographic directions, set Reference to Cell. GAMGI automatically shows a Cell entry, plus u, v, w entries to indicate the direction indices, plus a Vectors menu, to select the cell vectors to use, Conventional or Primitive. For the sake of simplicity, GAMGI does not accept 4-indice notation for planes or directions in hexagonal cells.

Pressing the mouse over a cell in the current layer, the cell identification is automatically written in the Cell entry. When a valid cell is found and its Type is Projection, the default Line page is automatically replaced by a Projection page.

By default, only one family of crystallographic directions is created. To create a set of families simultaneously, press the button Set (TODO). Atoms When Reference is set to Atoms, GAMGI automatically shows two Atom entries. Pressing the mouse sucessively over two non-colinear atoms in the current layer, the two entries become occupied and the direction defined. After pressing Ok, an error is shown if the atoms are coincident.
Home