Manybody aspects of positron annihilation in the electron gas
Abstract
We investigate positron annihilation in the electron gas as a case study for manybody theory, in particular, the Fermihypernettedchain EulerLagrange (FHNCEL) method. We examine several approximation schemes and show that one has to go up to the most sophisticated implementation of the theory available at the moment in order to get annihilation rates that agree reasonably well with experimental data. Even though there is basically just one number we look at, namely, the electronpositron pairdistribution function at zero distance, it is exactly this number that dictates how the full pair distribution behaves: in most cases, it falls off monotonously towards unity as the distance increases. Cases where the electronpositron pair distribution exhibits a dip are precursors to the formation of bound electronpositron pairs. The formation of electronpositron pairs is indicated by a divergence of the FHNCEL equations; from this we can estimate the density regime where positrons must be localized. This occurs in our calculations in the range 9.4⩽r_{s}⩽10, where r_{s} is the dimensionless density parameter of the electron liquid.
 Publication:

Physical Review B
 Pub Date:
 November 2003
 DOI:
 10.1103/PhysRevB.68.195118
 arXiv:
 arXiv:condmat/0311293
 Bibcode:
 2003PhRvB..68s5118A
 Keywords:

 78.70.Bj;
 71.10.Ca;
 Positron annihilation;
 Electron gas Fermi gas;
 Condensed Matter
 EPrint:
 To appear in Phys. Rev. B (2003)