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2.3 Basic structure types

Bonding in ionic structures – Coulomb interaction

Calculating the Madelung constant (for NaCl)

First term: attraction from the 6 nearest
12 8 6 neighbors
6
A    
...
2 3 4 Second term: repulsion (opposite sign)
from 12 next nearest neighbors

…

First coordination Second Third coordination
sphere coordination sphere sphere A converges to a value of 1.748.

A CN

Rock Salt 1.748 6

CsCl 1.763 8

Sphalerite 1.638 4

Fluorite 5.039 8