Positron-electron annihilation rates in an electron gas studied by variational Monte Carlo simulationE. Boronski
Polish Academy of Sciences, W. Trzebiatowski Institute for Low Temperature and Structure Research - P.O. Box 1410, 50-950 Wroclaw 2, Poland
received 29 April 2006; accepted in final form 19 June 2006
published online 5 July 2006
The studies of the electron-positron (e-p) interaction in condensed matter using the quantum Monte Carlo (QMC) simulations brought only fragmentary or incorrect results and have been suspended for a longer time. In the present work using the variational quantum Monte Carlo (VQMC) method correct and reasonable annihilation rates for a positron in an electron gas (EG) in a wide range of electron densities have been obtained. This has been achieved owing to an appropriate construction of the trial function which takes into account the 3-particle correlations (i.e. the dependence of the e-e interaction on the distance from the positron) and Friedel oscillations of the e-p correlation function. The annihilation rates have been found by "direct determination" of e-p contact densities on the basis of the variational trial function. We also have found the scheme for calculating of the momentum-dependent enhancement factors (MDEF), quantities not achievable within the MC method until now.
71.60.+z - Positron states.
02.70.Ss - Quantum Monte Carlo methods.
71.10.Ca - Electron gas, Fermi gas.
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