Negative thermal expansion of cubic silicon dicarbodiimide, Si(NCN)2, studied by ab initio lattice dynamics. / Li, Li; Refson, Keith; Dove, Martin T.

In: Journal of Physics: Condensed Matter, Vol. 32, No. 46, 465402, 25.08.2020, p. 1-10.

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We report an ab initio calculation of crystal structure and lattice dynamics of cubic silicon dicarbodiimide, Si(NCN)2, using density functional theory methods. The calculations reveal a low-energy spectrum of rigid unit modes that are shown to be associated with negative thermal expansion. Comparisons are drawn with the closely-related materials Zn(CN)2 and the cubic-cristobalite phase of SiO2. Instabilities in the spectrum of rigid unit modes point to the existence of disorder of the positions and orientations of the dicarbodiimide molecular anions.
Original languageEnglish
Article number465402
Pages (from-to)1-10
Number of pages10
JournalJournal of Physics: Condensed Matter
Issue number46
Early online date23 Jul 2020
Publication statusPublished - 25 Aug 2020
This open access research output is licenced under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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