Effect of the Positron Distribution on the Electron-Positron Momentum Density Calculated for SiC

To interpret positron annihilation data in solids in terms of the electron momentum density, both the electron-positron interaction and positron distribution have to be considered explicitly. In the present work the influence of the shape of the positron wave function on the calculated electron-positron momentum density in elemental SiC is discussed. It is shown that the form of the positron distribution in the Wigner-Seitz cell has a considerable effect on the resulting annihilation characteristics. Calculations were performed for SiC of 3C diamond structure within the linear muffin-tin orbital-atomic spheres approximation method.