Modeling the momentum distributions of annihilating electron-positron pairs in solids

  title={Modeling the momentum distributions of annihilating electron-positron pairs in solids},
  author={Ilja Makkonen and Mikko Hakala and Martti J. Puska},
  journal={Physical Review B},
Measuring the Doppler broadening of the positron annihilation radiation or the angular correlation between the two annihilation gamma quanta reflects the momentum distribution of electrons seen by positrons in the material. Vacancy-type defects in solids localize positrons and the measured spectra are sensitive to the detailed chemical and geometric environments of the defects. However, the measured information is indirect and when using it in defect identification comparisons with… 
First-principles calculations of momentum distributions of annihilating electron-positron pairs in defects in UO2.
It was shown that it should be possible to observe the fission gas incorporation in defects in UO2 using positron annihilation spectroscopy using positronic forces, and it was suggested that the Doppler broadening measurements can be especially useful for studying impurities and dopants in Uo2 and of mixed actinide oxides.
Enhancement Factors for Positron Annihilation on Valence and Core Orbitals of Noble-Gas Atoms
Annihilation momentum densities and vertex enhancement factors for positron annihilation on valence and core electrons of noble-gas atoms are calculated using many-body theory for s, p and d-wave
Surface states and positron annihilation spectroscopy: results and prospects from a first-principles approach
The trapping of positrons at the surface of a material can be exploited to study quite selectively the surface properties of the latter by means of positron annihilation spectroscopy techniques. To
Enhancement models of momentum densities of annihilating electron-positron pairs: The many-body picture of natural geminals
this by modeling the momentum density of annihilating electron-positron pairs using the framework of reduced density matrices, natural orbitals, and natural geminals (electron-positron pair wave
Energetics of positron states trapped at vacancies in solids
We report a computational first-principles study of positron trapping at vacancy defects in metals and semiconductors. The main emphasis is on the energetics of the trapping process including the
Improved generalized gradient approximation for positron states in solids
Several first-principles calculations of positron-annihilation characteristics in solids have added gradient corrections to the local-density approximation within the theory by Arponen and Pajanne
Exploring positron characteristics utilizing two new positron-electron correlation schemes based on multiple electronic structure calculation methods
We make a gradient correction to a new local density approximation form of positron–electron correlation. The positron lifetimes and affinities are then probed by using these two approximation forms


Theoretical and experimental study of positron annihilation with core electrons in solids.
A theory for calculating the momentum distribution of annihilating positron-electron pairs in solids and the comparison of the theoretical and experimental spectra for alloys and vacancy defects tests the theoretical description for the positron distribution in delocalized and localized states.
Momentum distributions of electron-positron pairs annihilating at vacancy clusters in Si
We report calculations of momentum densities of electron-positron pairs annihilating at various vacancy clusters in Si. The densities integrated along one direction, i.e., those corresponding to the
First-principles calculation of coincidence Doppler broadening of positron annihilation radiation
We report a first-principles method for calculating the momentum density of positron-electron pairs in materials, which can be accurately measured, in a wide momentum range, by means of coincidence
Calculation of positron states and annihilation in solids: A density-gradient-correction scheme.
Comparison with experiments shows systematic improvement in the predictive power of the theory compared to the local-density approximation results for positron states and annihilation characteristics.
Two-component density functional theory calculations of positron lifetimes for small vacancy clusters in silicon
The positron lifetimes for various vacancy clusters in silicon are calculated within the framework of the two-component electron-positron density functional theory. The effect of the trapped positron
Variational theory of multicomponent quantum fluids: An application to positron-electron plasmas at T=0.
  • Lantto
  • Physics
    Physical review. B, Condensed matter
  • 1987
This work makes use of the multicomponent Fermi hypernetted-chain method to calculate the energy and pair-correlation functions of this system and supports earlier theoretical predictions for the model electron-hole liquid and is in good agreement with available experimental evidence.
Construction of Electron-Positron Momentum Density from Pseudo-Wavefunctions with Better Accuracy
The coincidence Doppler spectra for Cu and Si have been calculated with the norm-conserving pseudopotential (NCPP) method as well as with the projector augmented-wave (PAW) method. The spectra
Gradient correction for positron states in solids.
The results for several metals and semiconductors show that the GGA systematically improves the predictive power of positron lifetime calculations over those based on the LDA.
Electron momentum density and Compton profiles in Lithium along $ $, $ $, and $ $ directions are calculated using Full-Potential Linear Augmented Plane Wave basis within generalized gradient