First-principles calculation of positron annihilation characteristics at metal vacancies

Korhonen, T.; Puska, Martti J.; Nieminen, Risto M.

doi:10.1103/physrevb.54.15016

Cited by 62 publications

(53 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The CS has been shown to yield for a given ionic structure lifetimes 29 and also other annihilation characteristics 12 in good agreement with two-component calculations based on the Boroński-Nieminen formalism.…”

Section: Vacancy Defects In Solidssupporting

confidence: 55%

See 1 more Smart Citation

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

2006

Self Cite

View full text Add to dashboard Cite

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 theoretically predicted spectra is indispensable. In this article we present a computational scheme for calculating momentum distributions of electron-positron pairs annihilating in solids. Valence electron states and their interaction with ion cores are described using the all-electron projector augmented-wave method, and atomic orbitals are used to describe the core states. We apply our numerical scheme to selected systems and compare three different enhancement ͑electron-positron correlation͒ schemes previously used in the calculation of momentum distributions of annihilating electron-positron pairs within the density-functional theory. We show that the use of a state-dependent enhancement scheme leads to better results than a position-dependent enhancement factor in the case of ratios of Doppler spectra between different systems. Further, we demonstrate the applicability of our scheme for studying vacancy-type defects in metals and semiconductors. Especially we study the effect of forces due to a positron localized at a vacancytype defect on the ionic relaxations.

show abstract

Section: Vacancy Defects In Solidssupporting

confidence: 55%

“…We integrate over the lowest lying positron band by calculating the positron wave function both at the ⌫ point and at the Brillouin zone boundary point L and using the average of the respective results. 29 …”

Section: A Calculation Of the Positron Statesmentioning

confidence: 99%

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

2006

Self Cite

View full text Add to dashboard Cite

show abstract

“…At the L point the wave functions are purely real as in the ⌫ point, but they change sign between the adjacent cells. The use of these two k points was recommended also by Korhonen et al 34 in the context of localized positron states at lattice defects. Korhonen et al justified the recommendation by real-space arguments.…”

Section: Brillouin-zone Samplingmentioning

confidence: 99%

Convergence of supercell calculations for point defects in semiconductors: Vacancy in silicon

et al. 1998

Self Cite

View full text Add to dashboard Cite

The convergence of first-principles supercell calculations for defects in semiconductors is studied with the vacancy in bulk Si as a test case. The ionic relaxations, defect formation energies, and ionization levels are calculated for supercell sizes of up to 216 atomic sites using several k-point meshes in the Brillouin-zone integrations. The energy dispersion, inherent for the deep defect states in the supercell approximation, and the long range of the ionic relaxations are shown to postpone the convergence so that conclusive results for the physical properties cannot be obtained before the supercell size is of the order of 128-216 atomic sites.

show abstract

“…In other words, the positron density is too delocalized when the supercell is not large enough. This has been addressed by Korhonen, Puska, and Nieminen (1996). Their remedy is to use two k points in the Brillouin zone, the À point and a point from the edge of the Brillouin zone of the superlattice at the top of the energy band.…”

Section: B Modeling Localized Positronsmentioning

confidence: 99%

“…Positrons localized at vacancies have been studied (Puska et al, 1989Alatalo, Puska, and Nieminen, 1993;Plazaola, Seitsonen, and Puska, 1994;Korhonen, Puska, and Nieminen, 1996;Barbiellini et al, 1997), also using the LMTO Green's function method (Puska et al, 1986). In most of the works the so-called atomic-sphere approximation (Skriver, 1984;Andersen, Jepsen, and Glötzel, 1985) has been made but also the full-potential variant has been used .…”

Section: F Numerical Approaches For Self-consistent Calculationsmentioning

confidence: 99%

Defect identification in semiconductors with positron annihilation: Experiment and theory

2013

View full text Add to dashboard Cite

Positron annihilation spectroscopy is particularly suitable for studying vacancy-type defects in semiconductors. Combining state-of-the-art experimental and theoretical methods allows for detailed identification of the defects and their chemical surroundings. Also charge states and defect levels in the band gap are accessible. In this review the main experimental and theoretical analysis techniques are described. The usage of these methods is illustrated through examples in technologically important elemental and compound semiconductors. Future challenges include the analysis of noncrystalline materials and of transient defect-related phenomena.

show abstract

First-principles calculation of positron annihilation characteristics at metal vacancies

Cited by 62 publications

References 37 publications

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

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

Convergence of supercell calculations for point defects in semiconductors: Vacancy in silicon

Defect identification in semiconductors with positron annihilation: Experiment and theory

Contact Info

Product

Resources

About