Total energies of crystal structures can be calculated to high precision using quantumbased density functional theory (DFT) methods, but the calculations can be time consuming and scale badly with system size. Boron carbide exhibits disorder in the distribution of boron and carbon atoms among the crystallographic sites. A cluster expansion of the DFT energy in a series of pairs, triplets, etc. ...

Boron carbide (B4C) is very hard, but its applications are hindered by stress-induced amorphous band formation. To explain this behavior, we used density function theory (Perdew-Burke-Ernzerhof flavor) to examine the response to shear along 11 plausible slip systems. We found that the (0111)/<1101> slip system has the lowest shear strength (consistent with previous experimental studies) and tha...