Abstract:
The energy-momentum resolved valence band structure of beryllium oxide has
been measured by electron momentum spectroscopy (EMS). Band dispersions, bandwidths
and intervalence bandgap, electron momentum density (EMD) and density of occupied
states have been extracted from the EMS data. The experimental results are compared
with band structure calculations performed within the full potential linear muffin-tin orbital
approximation. Our experimental bandwidths of 2.1 0.2 eV and 4.8 0.3 eV for the oxygen
s- and p-bands, respectively, are in accord with theoretical predictions as is the s-band EMD
after background subtraction. Contrary to the calculations, however, the measured p-band
EMD shows large intensity at the T point. The measured full valence bandwidth of 19.4 0.3
eV is at least 1.4 eV larger than the theory. The experiment also finds a significantly higher
value for the p-to-s-band EMD ratio in a broad momentum range compared to the theory.
