Parameterization C for the Tunable Intrinsic Ductility Potential (TIDP) due to Rajan et al. (2016). This is a family of pair potentials for which the intrinsic ductility can be tuned systematically from Parameterization A (most ductile) to Parameterization F (most brittle). Specifically, the elastic constants and critical energy release rate for Griffith cleavage, GIc, are held constant, while the critical energy release rate for dislocation emission, GIe, can be varied. The potential is applicable to 3D fcc/hcp crystals. This is a "toy potential" using dimensionless units. (A potential for 2D hexagonal lattices is also described in the paper.)