5. Linear ionic crystal. Consider a line of 2N ions of alternating charge =q with a repulsive potential energy A/R" betw
Posted: Mon May 23, 2022 10:52 am
5. Linear ionic crystal. Consider a line of 2N ions of alternating charge =q with a repulsive potential energy A/R" between nearest neighbors. (a) Show that at the equilibrium separation 2Nq* In 21 (CGS) U(R) ) RO n (b) Let the crystal be compressed so that Ro → Rol1 - 8). Show that the work done in compressing a unit length of the crystal has the leading term C8?, where (CGS) с (n-1)qlo 2 Ro To obtain the results in SI, replace qe by q°/47€). Note: We should not expect to ob- tain this result from the expression for U(Ro), but we must use the complete expres- sion for U(R).