Born–Mayer equation

The Born–Mayer equation is an equation that is used to calculate the lattice energy of a crystalline ionic compound. It is a refinement of the Born–Landé equation by using an improved repulsion term.


 * $$E =- \frac{N_AMz^+z^- e^2 }{4 \pi \epsilon_0 r_0}\left(1-\frac{\rho}{r_0}\right)$$

where:
 * NA = Avogadro constant;
 * M = Madelung constant, relating to the geometry of the crystal;
 * z+ = charge number of cation
 * z− = charge number of anion
 * e = elementary charge, 1.6022 C
 * &epsilon;0 = permittivity of free space
 * 4$\pi$&epsilon;0 = 1.112 C2/(J·m)
 * r0 = distance to closest ion
 * ρ = a constant dependent on the compressibility of the crystal; 30 pm works well for all alkali metal halides