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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Quantum Monte Carlo study of Doppler broadening of positron annihilation radiation in semiconductors and insulators
AU - Simula, Kristoffer
AU - Harkonen, J
AU - Zhelezova, I
AU - Drummond, Neil
AU - Tuomisto, F
AU - Makkonen, Ilja
PY - 2023/7/15
Y1 - 2023/7/15
N2 - Positron annihilation in solid-state matter can be utilized to detect and identify open-volume defects. The momentum distribution of the annihilation radiation is an important observable in positron-based measurements and can reveal information on the chemical surroundings of the defect sites. In this paper, we present a variational quantum Monte Carlo method for simulation of the momentum densities of annihilating electron-positron pairs in semiconductors and insulators. We study finite-size effects, effects of lattice vibrations, and different levels of trial wave functions. Small simulation cells and simple wave function forms are found to be sufficient for accurate calculations in the simulation of pristine lattices, enabling cheap accumulation of results. We compare calculated predictions of the Doppler broadening of the 511-keV 2γ annihilation line in aluminium nitride and silicon against experimental data measured from reference samples. Our results achieve better agreement with experiments in these materials than conventional state-of-the-art methods and prove that direct modeling of the electron-positron correlations is important for a supporting theory of positron annihilation spectroscopies.
AB - Positron annihilation in solid-state matter can be utilized to detect and identify open-volume defects. The momentum distribution of the annihilation radiation is an important observable in positron-based measurements and can reveal information on the chemical surroundings of the defect sites. In this paper, we present a variational quantum Monte Carlo method for simulation of the momentum densities of annihilating electron-positron pairs in semiconductors and insulators. We study finite-size effects, effects of lattice vibrations, and different levels of trial wave functions. Small simulation cells and simple wave function forms are found to be sufficient for accurate calculations in the simulation of pristine lattices, enabling cheap accumulation of results. We compare calculated predictions of the Doppler broadening of the 511-keV 2γ annihilation line in aluminium nitride and silicon against experimental data measured from reference samples. Our results achieve better agreement with experiments in these materials than conventional state-of-the-art methods and prove that direct modeling of the electron-positron correlations is important for a supporting theory of positron annihilation spectroscopies.
U2 - 10.1103/PhysRevB.108.045201
DO - 10.1103/PhysRevB.108.045201
M3 - Journal article
VL - 108
JO - Physical Review B: Condensed Matter and Materials Physics
JF - Physical Review B: Condensed Matter and Materials Physics
SN - 1098-0121
IS - 4
M1 - 045201
ER -