GAMGI Interfaces: Cell Modify

# Cell Modify

- Symmetry
- Volume
- Position
- Origin
- View

Change here the volume representation for a single cell or a list of cells.

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

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

### Type

Lattices can be represented using Conventional, Primitive or Wigner-Seitz cells, plus filtering volumes such as a Parallelepiped or a Sphere. Lattices can also be represented by the stereographic Projection of its crystallographic planes and directions (added by users, after the projection is created).

Cells with a Hexagonal system and a rhombohedral R lattice (corresponding to the seven R space groups when using the standard Hermann-Mauguin symbols), are always represented using the hexagonal axes and the obverse setting, when the chosen type is Conventional, and the rombohedral axes, when the chosen type is Primitive. Cells with a Hexagonal system and a primitive P lattice (corresponding to all the other space groups from 143 to 194 that are not R) are always represented using full hexagonal prismas, when the chosen type is Conventional, and one-third of the hexagonal prismas, when the chosen type is Primitive.

### N1, N2, N3

Change the number of cells to replicate, in the three directions of space, when the chosen type is Conventional, Primitive or Wigner-Seitz. When not needed, these parameters are disabled.

### V1, V2, V3, V23, V13, V12

A Parallelepiped filtering volume is defined by three edge lengths, V1, V2, V3, plus the three angles between them, V23, V13, V12. Each angle must be smaller than the sum of the other two and must be larger than the absolute difference of the other two, otherwise an error is produced.

A Sphere filtering volume is defined by the radius v1. When not needed, these parameters are disabled.

All nodes inside the volume representation are allocated (even if the user choosed to hide them). In Parallelepiped and Sphere volumes, a small tolerance (by default 1.0E-4) is added around the volume space to make sure that nodes in the borders are included. For example, a sphere with v1 = 1.0, filtering a cubic primitive lattice with a = 1.0, allocates 1 + 2 + 2 + 2 = 7 nodes (without the tolerance, the result could be undefined).
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