  Positron annihilation spectroscopy is often used to analyze the local
electronic structure of materials of technological interest. Reliable
theoretical tools are crucial to interpret the measured spectra. Here, we
propose a parameter-free gradient correction scheme for a local-density
approximation obtained from high quality quantum Monte Carlo data. The results
of our calculations compare favorably with positron affinity and lifetime
measurements opening new avenues for highly precise and advanced positron
characterization of materials.
