# The net potential energy EN between two adjacent ions is

# The net potential energy EN between two adjacent ions is

The net potential energy EN between two adjacent ions is sometimes represented by the expression

in which r is the interionic separation and C, D, and ? are constants whose values depend on the specific material.

(a) Derive an expression for the bonding energy E0 in terms of the equilibrium interionic separation r0 and the constants D and ? using the following procedure:

1. Differentiate EN with respect to r and set the resulting expression equal to zero.

2. Solve for C in terms of D, ?, and r0.

3. Determine the expression for E0 by substitution for C in Equation 2.12.

(b) Derive another expression for E0 in terms of r0, C, and ? using a procedure analogous to the one outlined in part (a).