“…An agreement of the calculated 1 IO meV GPa-' (6&) is only weakly pressure dependent) with experiment is not necessarily expected both because of the uncertainties in a: and a: (experimentally one typically measures the shift of band gap with pressure, which is proportional to ( -a , + a"), rather than a, or a, separately), and because of the limitations of our model, which neglects band hybridization in the conduction band (Akera et al 1988).…”