I was doing some basic density calculations for some work, and was trying to use the crystal structure parameters of graphite provided here: mp-48: C (hexagonal, P6_3/mmc, 194)
The c-parameter of graphite is quoted as 8.685 Angstrom, which implies a (002) X-ray diffraction peak of d=4.343 (at a little over 20 2theta for Cu K alpha) but this is incorrect, graphite is well known to have a d-spacing of 3.35 Angstrom, corresponding to a c-lattice parameter of 6.69 Angstrom, and a (002) peak at roughly 26.6 2theta.
Am I missing something here? Are the values quoted on the materials project calculated computationally? Or does that entry need to be updated?
Just thought I would raise it as I was confused.