Electron-positron interaction in light elements represented by atoms embedded in an electron gas

Mijnarends et al. (J. Phys. Condens. Matter 10 (1998) 10383) contested the best existing calculations of positron annihilation rates in jellium and crystal lattices, pointing in this way at deficiencies of existing theories of electron-positron interaction in these materials. In the present work, the local enhancement factors due to e+-e- interaction in Li, Be, B, C, N and O are computed in a consequent many-body approach for core and as concerns lithium also for conduction electrons and compared to the results of existing approximations to this problem which avoid direct many-body calculations in metals, i.e., the local density, generalized gradient and weighted density approximations, as well as to experimental data. Conclusions about positron lifetime and e+-e- correlation energy are also presented. They support the results of Mijnarends et al. concerning applicability of the LDA approximation to e+-e- interaction and validity of the Boroński-Nieminen formula for the correlation function.