OPTICAL CONDUCTIVITY OF THE HOLSTEIN MODEL AT LOW DENSITY

2000 ◽  
Vol 14 (25n27) ◽  
pp. 3020-3025 ◽  
Author(s):  
S. FRATINI ◽  
F. DE PASQUALE ◽  
S. CIUCHI
Keyword(s):  
Optical Conductivity ◽  
Weak Coupling ◽  
Small Polaron ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spectral Weight ◽  
Low Density ◽  
Intermediate Coupling ◽  
Holstein Model ◽  
Low Density Limit

We apply the dynamical mean field theory to calculate the low-density limit of the small polaron optical conductivity in the Holstein model. Classical schemes of approximation are recovered in weak coupling and in the adiabatic and anti-adiabatic strong coupling limits. Such schemes are not suitable for the intermediate coupling regime, where our theory gives an anomalous behaviour of the spectral weight at low energy as the temperature decreases.

scholarly journals Weak-coupling Mean-field Theory of Magnetic Properties of NiGa2S4

2020 ◽  
Vol 89 (2) ◽  
pp. 024704
Author(s):  
Takuji Nomura ◽  
Yuji Yamamoto ◽  
Kenji Yoshii
Keyword(s):  
Field Theory ◽  
Magnetic Properties ◽  
Weak Coupling ◽  
Mean Field Theory ◽  
Mean Field

Isotope effects in the Hubbard-Holstein model within dynamical mean-field theory

2006 ◽  
Vol 74 (20) ◽  
Author(s):  
P. Paci ◽  
M. Capone ◽  
E. Cappelluti ◽  
S. Ciuchi ◽  
C. Grimaldi
Keyword(s):  
Field Theory ◽  
Isotope Effects ◽  
Mean Field Theory ◽  
Mean Field ◽  
Dynamical Mean Field Theory ◽  
Holstein Model

scholarly journals Evolution of the Kondo lattice electronic structure above the transport coherence temperature

2020 ◽  
Vol 117 (38) ◽  
pp. 23467-23476
Author(s):  
Sooyoung Jang ◽  
J. D. Denlinger ◽  
J. W. Allen ◽  
V. S. Zapf ◽  
M. B. Maple ◽  
...  
Keyword(s):  
Electric Field ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spectral Weight ◽  
Kondo Lattice ◽  
Crystalline Electric Field ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sufficient Detail ◽  
Arpes Data

The temperature-dependent evolution of the Kondo lattice is a long-standing topic of theoretical and experimental investigation and yet it lacks a truly microscopic description of the relation of the basic f-c hybridization processes to the fundamental temperature scales of Kondo screening and Fermi-liquid lattice coherence. Here, the temperature dependence of f-c hybridized band dispersions and Fermi-energy f spectral weight in the Kondo lattice system CeCoIn5is investigated using f-resonant angle-resolved photoemission spectroscopy (ARPES) with sufficient detail to allow direct comparison to first-principles dynamical mean-field theory (DMFT) calculations containing full realism of crystalline electric-field states. The ARPES results, for two orthogonal (001) and (100) cleaved surfaces and three different f-c hybridization configurations, with additional microscopic insight provided by DMFT, reveal f participation in the Fermi surface at temperatures much higher than the lattice coherence temperature,T*≈45K, commonly believed to be the onset for such behavior. The DMFT results show the role of crystalline electric-field (CEF) splittings in this behavior and a T-dependent CEF degeneracy crossover belowT*is specifically highlighted. A recent ARPES report of low T Luttinger theorem failure for CeCoIn5is shown to be unjustified by current ARPES data and is not found in the theory.

Metallized ε-FeOOH and the heterogeneous electrical conductivity structure in the lower mantle

2020 ◽  
Author(s):  
Yukai Zhuang ◽  
Zhongxun Cui ◽  
Ruilian Tang ◽  
Renbiao Tao ◽  
Mingqiang Hou ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Lower Mantle ◽  
Small Polaron ◽  
Mean Field Theory ◽  
Mean Field ◽  
Electron Conduction ◽  
Abrupt Jump ◽  
Conductivity Structure ◽  
Local Areas ◽  
Key Factor

Abstract Electrical heterogeneity at the depth of 900-1400 km in Earth’s interior is a key factor to constrain the minor phase composition of the lower mantle. However, prevailing mineralogical models including Fe- or Al-enriched silicates or ferropericlase are insufficient to explain the ultra-high electrical conductivity in local areas of subduction slabs. Here, we measure the electrical conductivity of ε-FeOOH up to 61 GPa. A 3-order abrupt jump of electrical conductivity is observed in 45-50 GPa, reaching 1.24±0.19 × 103 S/m at 61 GPa. Density mean field theory simulations suggest that ε-FeOOH undergoes a Mott-type electronic transition, which leads the conduction mechanism to switch from small polaron conduction to free electron conduction. Compared with bridgmanite, ferropericlase and conventional mantle compositional models, the electrical conductivity of the metallic ε-FeOOH is 1-3 orders of magnitude higher. Minor or moderate incorporation of metallic ε-FeOOH into the ambient lower mantle could reproduce the observed electrical heterogeneity derived from geomagnetic data at 900-1400 km depth.

scholarly journals Active matter in infinite dimensions: Fokker–Planck equation and dynamical mean-field theory at low density

2021 ◽  
Vol 155 (17) ◽  
pp. 174106
Author(s):  
Thibaut Arnoulx de Pirey ◽  
Alessandro Manacorda ◽  
Frédéric van Wijland ◽  
Francesco Zamponi
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Planck Equation ◽  
Dynamical Mean Field Theory ◽  
Low Density ◽  
Active Matter ◽  
Infinite Dimensions ◽  
Fokker Planck Equation ◽  
Fokker Planck
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