Graphene's Hamiltonian contains first order derivatives (from the momentum operators) which aren't invariant under simple spatial rotations. So it initially appears to me that it isn't invariant under rotation. From reading around I see that we also have to perform a rotation on the Pauli matrices that always appear with these operators which would then leave the Hamiltonian invariant. I don't understand how to do this rotation or why this is the case? Any help would be greatly appreciated(adsbygoogle = window.adsbygoogle || []).push({});

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# I How is Graphene's Hamiltonian rotationally invariant?

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