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arXiv · 1903.00778

Disruption of the $sp^2$ bonding by the compression of the $π$-electronic orbitals of graphene at various stacking orders

Yiwei Sun·David Holec·Dominik Nöger·David Dunstan·Colin Humphreys
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Abstract

We investigate the behaviour of the $π$-electrons under compression and the effect of the stacking order of graphene layers. First we find that electrons can hardly be squeezed through the $sp^2$ network, regardless of the stacking order. The largely deformed electronic orbitals (mainly those of $π$-electrons) under compression along the $\textit{c}$-axis increase interlayer interaction between graphene layers as expected, but surprisingly in a similar way for the A-A and Bernal stacking. On the other hand, the large out-of-plane compression shifts the in-plane phonon frequencies of A-A stacked graphene layers significantly and very differently from Bernal stacked layers. We attribute these results to the $sp^2$-electrons filling the low-density central area in a carbon hexagon under compression for the A-A stacking, hence resulting in a non-monotonic change of the $sp^2$-bonding. The results strongly suggest not to ignore 3D features of a 2D material.

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Yiwei Sun, David Holec, Dominik Nöger, David Dunstan, Colin Humphreys. 2019-03-02. Disruption of the $sp^2$ bonding by the compression of the $π$-electronic orbitals of graphene at various stacking orders. https://doi.org/10.1103/physrevb.101.125421

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