Entropy driven stabilization of energetically unstable crystal structures explained from first principles theory
2008 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 100, no 9, 095901- p.Article in journal (Refereed) Published
Conventional methods to calculate the thermodynamics of crystals evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the body-centered cubic (bcc) crystal structure when it appears as a high-temperature phase of many metals. A method for calculating temperature dependent phonon spectra self-consistently from first principles has been developed to address this issue. The method combines concepts from Born's interatomic self-consistent phonon approach with first principles calculations of accurate interatomic forces in a supercell. The method has been tested on the high-temperature bcc phase of Ti, Zr, and Hf, as representative examples, and is found to reproduce the observed high-temperature phonon frequencies with good accuracy.
Place, publisher, year, edition, pages
2008. Vol. 100, no 9, 095901- p.
Thermal expansion; thermomechanical effects, Phonon states and bands, normal modes, and phonon dispersion, Transition metals and alloys
IdentifiersURN: urn:nbn:se:uu:diva-96177DOI: 10.1103/PhysRevLett.100.095901ISI: 000253764500047OAI: oai:DiVA.org:uu-96177DiVA: diva2:170663