Europhys. Lett.
Volume 75, Number 3, August 2006
Page(s) 475 - 481
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 05 July 2006
Europhys. Lett., 75 (3), pp. 475-481 (2006)
DOI: 10.1209/epl/i2006-10134-5

Positron-electron annihilation rates in an electron gas studied by variational Monte Carlo simulation

E. 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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