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Anharmonic phonon frequency shift in MgB2

Michele Lazzeri·Matteo Calandra·Francesco Mauri
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Abstract

We compute the anharmonic shift of the phonon frequencies in MgB2, using density functional theory. We explicitly take into account the scattering between different phonon modes at different q-points in the Brillouin zone. The shift of the E2g mode at the Gamma point is +5 % of the harmonic frequency. This result comes from the cancellation between the contributions of the four- and three-phonon scattering, respectively +10 % and -5 %. A similar shift is predicted at the A point, in agreement with inelastic X-ray scattering phonon-dispersion measurements. A smaller shift is observed at the M point.

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Michele Lazzeri, Matteo Calandra, Francesco Mauri. 2003-06-25. Anharmonic phonon frequency shift in MgB2. https://doi.org/10.1103/physrevb.68.220509

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