Rock salt ( ) crystallises as a face-centred cubic lattice with a two-ion basis
PHYSICS · Subjective · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Lattice dynamics and thermal properties of solids · Lattice dynamics and thermal properties of solids
Condensed Matter Physics, Ch Einstein, Debye and the heat capacity of solids
Problem
Rock salt (NaCl) crystallises as a face-centred cubic lattice with a two-ion basis, one formula unit per primitive cell (Chapter 1). Chapter 5 showed that a primitive cell of p atoms carries 3p branches, one mode for every allowed wavevector in each branch. Using that branch count together with this chapter's classical rule that every mode holds kBT, find the Dulong-Petit molar heat capacity of rock salt, per mole of NaCl formula units.