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Updated: Dec 14, 2025

Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics
Published on: September 28, 2016
Negative thermal expansion of cubic silicon dicarbodiimide, Si(NCN)2, studied byab initiolattice dynamics
Li Li1,2, Keith Refson3,4, Martin T Dove5,6
1College of Physics, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China.
Abstract:
We report anab initiocalculation 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)2and 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.
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