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arXiv · 1311.1497

Ideal strength and phonon instability of strained monolayer materials

Eric B. Isaacs·Chris A. Marianetti
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Abstract

The ideal strength of monolayer materials possessing semimetallic, semiconducting, and insulating ground states is computed using density functional theory. Here we show that, as in graphene, a soft mode occurs at the K-point in BN, graphane, and MoS$_2$, while not in silicene. The transition is first-order in all cases except graphene. In BN and graphane the soft mode corresponds to a Kekul{\'e}-like distortion similar to that of graphene, while MoS$_2$ has a distinct distortion. The phase transitions for BN, graphane, and MoS$_2$ are not associated with the opening of a band gap, which indicates that Fermi surface nesting is not the driving force. We perform an energy decomposition that demonstrates why the soft modes at the K-point are unique and how strain drives the phonon instability.

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Eric B. Isaacs, Chris A. Marianetti. 2013-11-06. Ideal strength and phonon instability of strained monolayer materials. https://doi.org/10.1103/physrevb.89.184111

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