Evaluation of positron annihilation in Beryllium

A band theoretical calculation of angular distribution of annihilation photons (ADAP ) and the positron lifetime, up to and including higher momentum components is reported. The results obtained using biquadratic quasianalytic integration schemes for all Brillouin zone integrals, compare favorably with existing experimental data. There are, however, significant structures in the ADAP curve obtained than in the experimental curves.