Index of a group-subgroup pair
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The program INDEX calculates the index of a group subgroup pair. The index can be calculated in two different ways given:
- Option A
- The space group ITA numbers.
- The number of formula units per conventional unit cell.
- Option B
- The space group ITA numbers.
- The lattice parameters.
The number of formula units per conventional unit cell Zc is simply related to the number Z of formula units per primitive unit cell via the so-called centring factor f, Z=Zc/f, with f=1 for primitive lattices, 2 for I-, C-, B-, A- centred, 3 for R-centred and 4 for F-centred lattice.
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