Structures of bulk hexagonal post transition metal chalcogenides from dispersion-corrected density functional theory

Magorrian, Samuel and Zolyomi, Viktor and Drummond, Neil (2021) Structures of bulk hexagonal post transition metal chalcogenides from dispersion-corrected density functional theory. Physical Review B: Condensed Matter and Materials Physics, 103 (9). ISSN 1098-0121

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Abstract

We use dispersion-corrected density functional theory to determine the relative energies of competing polytypes of bulk layered hexagonal post transition metal chalcogenides to search for the most stable structures of these potentially technologically important semiconductors. We show that there is some degree of consensus among dispersion-corrected exchange-correlation functionals regarding the energetic orderings of polytypes, but we find that for each material there are multiple stacking orders with relative energies of less than 1 meV per monolayer unit cell, implying that stacking faults are expected to be abundant in all post transition metal chalcogenides. By fitting a simple model to all our energy data, we predict that the most stable hexagonal structure has the P63/mmc space group in each case but that the stacking order differs between GaS, GaSe, GaTe, and InS, on the one hand, and InSe and InTe, on the other. At zero pressure, the relative energies obtained with different functionals disagree by around 1–5 meV per monolayer unit cell, which is not sufficient to identify the most stable structure unambiguously; however, multigigapascal pressures reduce the number of competing phases significantly. At higher pressures, an AB′-stacked structure of the most stable monolayer polytype is found to be the most stable bulk structure.

Item Type:
Journal Article
Journal or Publication Title:
Physical Review B: Condensed Matter and Materials Physics
Additional Information:
© 2021 American Physical Society
ID Code:
153368
Deposited By:
Deposited On:
01 Apr 2021 15:35
Refereed?:
Yes
Published?:
Published
Last Modified:
20 Jun 2021 06:12