Condensed Matter Physics - Crystal Binding : Ionic Crystals / Calculation of Repulsive Exponent

In an ionic crystal there are two types of interactions- the long range Coulomb’s electrostatic interaction which may be attractive or repulsive in nature,and the other is short range repulsive interaction which comes into play when the inter ionic distance becomes so small that the electronic clouds of ions start overlapping. Coulomb’s electrostatic interaction energy is inversely proportional to the inter ionic distance r. There is not such a definite relationship between the short range repulsive energy and the distance r. In general this energy is inversely proportional to r raised to the power n. This n is called repulsive exponent. It’s the characteristic of the crystal and it varies by some extent ,crystal to crystal . How this repulsive exponent can be determined in terms of adiabatic compressibility of the crystal ,has been discussed in this video.