# Crystal structure

## `periodictable.crystal_structure`

Crystal structure data.

Adds crystal_structure to the periodic table. Each crystal structure is a dictionary which contains the key ‘symmetry’. Depending on the value of crystal_structure[‘symmetry’], one or more parameters ‘a’, ‘c/a’, ‘b/a’, ‘d’, and ‘alpha’ may be present according to the following table:

Crystal lattice parameters
Symmetry | Parameters
--- | ---
atom |
diatom | d
BCC | a
fcc | a
hcp | c/a, a
Tetragonal | c/a, a
Cubic | a
Diamond | a
Orthorhombic | c/a, a, b/a
Rhombohedral | a, alpha
SC | a
Monoclinic |

Example:

    >>> import periodictable as elements
    >>> print(elements.C.crystal_structure['symmetry'])
    Diamond
    >>> print(elements.C.crystal_structure['a'])
    3.57

This data is from Ashcroft and Mermin.

`periodictable.crystal_structure.``init`(table, reload=False)

  Add crystal_structure field to the element properties.