Nonadiabatic Fluctuations and the ChargeDensityWave Transition in OneDimensional ElectronPhonon Systems: A Dynamic SelfConsistent Theory
Abstract
The Peierls instability in onedimensional electronphonon systems is known to be qualitatively well described by the meanfield theory, however the related selfconsistent problem so far has only been able to predict a partial suppression of the transition even with proper account of classical lattice fluctuations. Here the HartreeFock approximation scheme is extended to the full quantum regime, by mapping the momentumfrequency spectrum of orderparameter fluctuations onto a continuous twoparameter space. For the onedimensional halffilled SuSchriefferHeeger model the ratio d=Ω/2π T_{c}^{0}, where Ω is the characteristic phonon frequency and 2π T_{c}^{0} the lowest finite phonon Matsubara frequency at the meanfield critical point T_{c}^{0}, provides a natural measure of the adiabaticity of lattice fluctuations. By integrating out finitefrequency phonons, it is found that a variation of d from the classical regime d=0 continuously connects T_{c}^{0} to a zerotemperature chargedensitywave transition setting up at a finite crossover d=d_{c}. This finite crossover decreases within the range 0≤ d≈ 1 as the electronphonon coupling strength increases but remaining small enough for weakcoupling considerations to still hold. Implications of T_{c} suppression on the Ginzburg criterion is discussed, and evidence is given of a possible coherent description of the chargedensitywave problem within the framework of a renormalized meanfield theory encompassing several aspects of the transition including its thermodynamics close to the quantum critical point.
 Publication:

Journal of the Physical Society of Japan
 Pub Date:
 February 2013
 DOI:
 10.7566/JPSJ.82.024003
 arXiv:
 arXiv:2110.00559
 Bibcode:
 2013JPSJ...82b4003D
 Keywords:

 Condensed Matter  Strongly Correlated Electrons;
 Condensed Matter  Statistical Mechanics
 EPrint:
 20 pages, 8 figures