Frustrated about defects

I would have thought that the solid state of something as "simple" as elemental boron would be both well understood and "boring". However, that is not the case. There is a beautiful paper from Giulia Galli's group. A few things I learnt about beta-rhombohedral boron.

• Boron tends to form three centre two electron bonds.
• It contains 320 atoms per hexagonal unit cell! 6 out of 20 crystallographic sites are only partially occupied. 
• The defect formation energy is negative leading to macroscopic numbers of intrinsic defects.
• The occupancy of the defects can be described in terms of a generalised Ising spin model on an expanded Kagome lattice.
• This Ising model describes the geometrical frustration associated with the defects, and the residual entropy present at zero temperature.

I am curious as to whether there is any need to take into account quantum fluctuations.