We compute, from first-principles, the frequency of the phonons associated to the Raman G-bands in a graphene monolayer and in metallic nanotubes as a function of the charge doping. In both cases, the frequency displays an important measurable shift in the range of doping reached experimentally. As a consequence, Raman spectroscopy can be used as a direct probe of the doping of these systems. Calculations are done using (i) the adiabatic Born-Oppenheimer approximation and (ii) time-dependent perturbation theory to explore dynamic effects beyond this approximation. The two approaches provide very different results. The frequency shift of the G-band in graphene and of the G(-) in metallic tubes represent remarkable failures of the adiabatic Born-Oppenheimer approximation. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Breakdown of the adiabatic approximation in a doped graphene monolayer and in metallic carbon nanotubes / Lazzeri, Michele; Saitta, A. Marco; Mauri, Francesco. - In: PHYSICA STATUS SOLIDI B-BASIC RESEARCH. - ISSN 0370-1972. - 244:11(2007), pp. 4118-4123. [10.1002/pssb.200776106]
Breakdown of the adiabatic approximation in a doped graphene monolayer and in metallic carbon nanotubes
Mauri, Francesco
2007
Abstract
We compute, from first-principles, the frequency of the phonons associated to the Raman G-bands in a graphene monolayer and in metallic nanotubes as a function of the charge doping. In both cases, the frequency displays an important measurable shift in the range of doping reached experimentally. As a consequence, Raman spectroscopy can be used as a direct probe of the doping of these systems. Calculations are done using (i) the adiabatic Born-Oppenheimer approximation and (ii) time-dependent perturbation theory to explore dynamic effects beyond this approximation. The two approaches provide very different results. The frequency shift of the G-band in graphene and of the G(-) in metallic tubes represent remarkable failures of the adiabatic Born-Oppenheimer approximation. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.