Ab initio lattice dynamics and thermal expansion of Cu2 O

Klaus Peter Bohnen, Rolf Heid, Lothar Pintschovius, Aloysius Soon, Catherine Stampfl

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Using ab initio density-functional perturbation theory the lattice dynamics of Cu2 O has been extensively studied. Discrepancies with older neutron-scattering results triggered a neutron-scattering investigation of our own which confirmed the theoretical prediction. Based on the accurate description of the phonon dispersion the vibrational part of the free energy was calculated as a function of lattice constant and temperature. The thermal expansion could be obtained in good agreement with experiments. For T<300 K negative thermal expansion (NTE) was observed while for higher temperatures normal thermal expansion was obtained. The origin of the NTE is due to anomalous behavior of phonon modes with energies <20 meV which is highly mode and wave-vector sensitive. Our calculations also showed that free energies based on the exact phonon dispersion and those based on an Einstein-model description (widely used) differed by more than 20%, which clearly indicates the importance of proper phonon-dispersion treatment for obtaining reliable thermodynamic data.

Original languageEnglish
Article number134304
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume80
Issue number13
DOIs
Publication statusPublished - 2009 Oct 22

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Lattice vibrations
Thermal expansion
thermal expansion
Neutron scattering
Free energy
expansion
neutron scattering
free energy
Lattice constants
Thermodynamics
Temperature
perturbation theory
thermodynamics
predictions
Experiments
Negative thermal expansion
temperature
energy

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Bohnen, Klaus Peter ; Heid, Rolf ; Pintschovius, Lothar ; Soon, Aloysius ; Stampfl, Catherine. / Ab initio lattice dynamics and thermal expansion of Cu2 O. In: Physical Review B - Condensed Matter and Materials Physics. 2009 ; Vol. 80, No. 13.
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Ab initio lattice dynamics and thermal expansion of Cu2 O. / Bohnen, Klaus Peter; Heid, Rolf; Pintschovius, Lothar; Soon, Aloysius; Stampfl, Catherine.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 80, No. 13, 134304, 22.10.2009.

Research output: Contribution to journalArticle

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