Naslov
Ab initio study of the stability of high pressure phases in II-VI semiconductors

Autori
Kirin, Davor ; Lukačević, Igor

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Programme Abstracts of Invited Talks and Abstracts of Posters / Gebauer, R. ; Mauri, F. ; Vanderbilt, D. - Trst : International Centre for Theoretical Physics (ICTP), 2007, 129-129

Skup
13th International Workshop on Computational Physics and Materials Science: Total Energy and Force Methods

Mjesto i datum
Trst, Italija, 11.01.2007. - 13.01.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
DFT ; phase transitions ; lattice dynamics

Sažetak
The study of pressure induced phase transitions has been rapidly expanding field of research during the past few decades. It was discovered that many semiconductors have a rich phase diagram, as a function of pressure and temperature, with a number of phases, which were not known before. The understanding of the mechanism of high pressure phase transitions at microscopic level is far from complete and more theoretical models are required. We investigated the stability of the rocksalt structure with respect to the high pressure Cmcm structure was investigated for several II-VI semiconductors (ZnS, ZnSe, CdS and CdSe). The lattice dynamics calculations reveal that the rocksalt structure is unstable with respect to transversal acoustic mode at the Brillouin zone boundary. The phase transition is of the second order, associated with cell doubling in the high pressure Cmcm phase with frozen in deformation. The present calculation gives the transition pressure more accuratelly then classical method, which uses the common tangent. Since the volume change at the transition is very small or zero in all studied crystals, transitions were estimated from the pressure at which the frequency of zone boundary transversal acoustic mode goes to zero at certain pressure. The observed pressures of the phase transitions in structural measurements were reproduced more accurately then in previous calculations and the difference between observed and calculated transition pressure is well below 10%.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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