Charge density wave and quantum fluctuations in a molecular crystal

We consider an electron-phonon system in two and three dimensions on square, hexagonal, and cubic lattices. The model is a modification of the standard Holstein model where the optical branch is appropriately curved in order to have a reflection positive Hamiltonian. Using infrared bounds together with a recent result on the coexistence of long-range order for electron and phonon fields, we prove that, at sufficiently low temperatures and sufficiently strong electron-phonon coupling, there is a Peierls instability towards a period two charge-density wave at half-filling. Our results take into account the quantum fluctuations of the elastic field in a rigorous way and are therefore independent of any adiabatic approximation. The strong coupling and low-temperature regime found here is independent of the strength of the quantum fluctuations of the elastic field.

Published in:
Physical Review B, 60, 19, 13484-13491

 Record created 2007-02-16, last modified 2018-03-17

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