The net potential energy en between two adjacent ions is sometimes represented by the expression e, m3 + d exp (2.18) in which r is the interionic separation and c, d, and rho are constants whose values depend on the specific material (a) derive an expression for the bonding energy eo in terms of the equilibrium interionic separation ro and the constants d and p using the following procedure: (i) differentiate en with respect to r, and set the resulting expression equal to zero. (ii) solve for c in terms of d, p, and ro i) determine the expression for e by substitution for c in equation 2.18 (b) derive another expression for eo in terms of ro, c, and p using a procedure analogous to the one outlined in part