Spin-orbit splitting, Fermi surface topology, and charge-density-wave gapping in 2H-TaSe2

Empirical tight-binding calculations on the layer compound 2H-TaSe2 have been performed and are found to replicate the basic phenomenology of Fermi surface topology and charge-density-wave gapping as revealed by angle-resolved photoemission spectroscopy (ARPES). The recently discovered piece of Fermi surface having a dog's bone shape is a consequence of the large spin-orbit splitting of Ta 5d levels. The 3x3 reconstruction, simulated here by bond strengthenings and weakenings, gives rise to gapping, predominantly on the K(H)-centered Fermi surface pocket in agreement with ARPES data. The concept of nesting is not used in the analysis.