Nonadiabatic Kohn Anomaly in a Doped Graphene Monolayer

2006/11/28 by Michele Lazzeri, Francesco Mauri · 551 citations
Materials Science · Physics and Astronomy · #Adiabatic process #Adiabatic theorem #Anomaly (physics) #Condensed matter physics #Doping #Graphene #Graphene research and applications #Perturbation theory (quantum mechanics) #Phonon #Physics #Quantum and electron transport phenomena #Quantum mechanics #Topological Materials and Phenomena #cond-mat.mes-hall #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevlett.97.266407

published in Physical Review Letters 97(26), 266407 (American Physical Society) · 5 pages, 3 figures, Accepted by Phys. Rev. Lett

arxiv created 2006/11/28 · openalex publication_date 2006/12/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We compute, from first principles, the frequency of the E(2g), Gamma phonon (Raman G band) of graphene, as a function of the charge doping. 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. While the adiabatic phonon frequency weakly depends on the doping, the dynamic one rapidly varies because of a Kohn anomaly. The adiabatic approximation is considered valid in most materials. Here, we show that doped graphene is a spectacular example where this approximation miserably fails.

Citations

• Phonons and related crystal properties from density-functional perturbation theory
• Generalized Gradient Approximation Made Simple
• Electric Field Effect in Atomically Thin Carbon Films
• Soft self-consistent pseudopotentials in a generalized eigenvalue formalism
• Experimental observation of the quantum Hall effect and Berry's phase in graphene

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