Rms thermal dilation of crystal cell (a) Estimate for 300 K the root mean square thermal dilation V/V for a primitive cell of sodium. Take

Rms thermal dilation of crystal cell
(a) Estimate for 300 K the root mean square thermal dilation ΔV/V for a primitive cell of sodium. Take the bulk modulus as 7 x 1010 erg cm-3. Note that the Debye temperature 158 K is less than 300 K, so that the thermal energy is of the order of kBT.
(b) Use this result to estimate the root mean square thermal fluctuation Δa/a of the lattice parameter.