# Superficial and molecular energies

Where n_{0} is the number of molecules contained per square meter of layer, the relationship between the energy per surface unit Es and the energy per molecule Em is:

This relationship applies to E_{cou} and E_{flx}. However, crystallization energy typically concerns the molecule. However, where N_{0} is the number of molecules per
volume unit, we have:

where Evcris is the crystallization energy per volume unit.

# Surface energy

The interfacial crystal-solution energy depends on:

- - temperature;
- - the characteristics of the solution and of the crystal.

According to Onsager [ONS 44], the linear energy of the edge of a face is as follows:

where J and J' are the interaction energies in two perpendicular directions. This energy is cancelled for:

When this temperature is reached, the crystal growth becomes rough. This is thermal transition.

The surface energy is: a: dimension of one molecule (m)

For conditions close to ambience, Mersmann proposed the following correlation for surface energy:

p_{s}: real density of crystal (kg.m^{-3})

M: molar mass (kg.kmol^{-1})

N_{a}: Avogadro number (6.02.10^{26} molecules.kmol^{-1})
cL : molar concentration of the saturation liquor