Work in progress. See also W. E. Pickett, Rev. Mod. Phys. 61, 433-512 (1989). Recent data from Z. X. Shen and collaborators looks as follows:

The pink line indicates the Fermi surface from local density approximation calculations done in 1987; see W. E. Pickett, Rev. Mod. Phys. 61, 433-512 (1989), especially Figure 19, page 453.