Calculation of Positron Response from Embedded Nanoparticles

Nanoparticles embedded in a matrix can trap positrons under certain conditions. In such cases nanoparticles can be effectively studied by means of positron annihilation because positron annihilation characteristics contain information related to nanoparticles' electronic and atomic structure. Of great importance is to calculate the positron response from such nanoparticles. Then, nanoparticles can, in principle, be identified by comparing the measured and calculated positron annihilation response. For this purpose we present an efficient computational method based on the well-known atomic superposition technique. This method is explained in detail, justified on the basis of first principles calculations, and applied to Cu nanoparticles embedded in the Fe matrix.