Excitation spectrum of TTF-TCNQ: a finite temperature calculation

AbstractIn this paper we study the excitation spectrum of the organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) using finite temperature calculations. The effect of electronelectron interaction is considered within the random phase approximation (RPA). Our results show the temperature dependent plasmon and dipolar mode corresponding qualitatively to the modes obtained previously using zero temperature formalism assigned to the observed excitations at 10 meV and 0.75 eV. These modes have an essential influence on the energy-loss function. The obtained results are in good qualitative agreement with the optical and EELS data of TTF-TCNQ.

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Transport properties of bilayer graphene due to charged impurity scattering: Temperature-dependent screening and substrate effects

International Journal of Modern Physics B ◽

10.1142/s0217979218500649 ◽

2018 ◽

Vol 32 (06) ◽

pp. 1850064

Author(s):

Dang Khanh Linh ◽

Nguyen Quoc Khanh

Keyword(s):

Finite Temperature ◽

Random Phase Approximation ◽

Random Phase ◽

Thermal Conductance ◽

Impurity Scattering ◽

Bilayer Graphene ◽

Zero Temperature ◽

Temperature Dependent ◽

Temperature Conductivity ◽

Charged Impurity Scattering

We calculate the zero-temperature conductivity of bilayer graphene (BLG) impacted by Coulomb impurity scattering using four different screening models: unscreened, Thomas–Fermi (TF), overscreened and random phase approximation (RPA). We also calculate the conductivity and thermal conductance of BLG using TF, zero- and finite-temperature RPA screening functions. We find large differences between the results of the models and show that TF and finite-temperature RPA give similar results for diffusion thermopower S[Formula: see text]. Using the finite-temperature RPA, we calculate temperature and density dependence of S[Formula: see text] in BLG on SiO2, HfO2 substrates and suspended BLG for different values of interlayer distance c and distance between the first layer and the substrate d.

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Finite-temperature full random-phase approximation of bandgap narrowing in quasi-neutral regions: Theory including nonparabolicity and application to silicon and InGaAs

Journal of Applied Physics ◽

10.1063/5.0051055 ◽

2021 ◽

Vol 130 (1) ◽

pp. 015703

Author(s):

A. Schenk

Keyword(s):

Finite Temperature ◽

Random Phase Approximation ◽

Random Phase ◽

Phase Approximation ◽

Bandgap Narrowing

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ν − ν interactions in supernovae environments as a function of density and temperature

International Journal of Modern Physics E ◽

10.1142/s021830132150018x ◽

2021 ◽

Vol 30 (03) ◽

pp. 2150018

Author(s):

M. P. Colombi ◽

O. Civitarese ◽

A. V. Penacchioni

Keyword(s):

Density Dependence ◽

Random Phase Approximation ◽

Random Phase ◽

Neutrino Energy ◽

Phase Approximation ◽

Temperature Dependent ◽

Energy Distributions ◽

Quasi Particle ◽

Collective Response ◽

Bogoliubov Transformations

Neutrinos in astrophysical environments, such as Supernovae (SNe), may interact through pair interactions. These interactions are density and temperature-dependent. Under certain conditions, a neutrino-condensate may form. In this work, we have adapted the separable nonlocal pairing interactions to the SN conditions and studied the temperature and density dependence of the pairing gap as well as the collective response with respect to these variables. We have applied the Bogoliubov transformations and solved the Bardeen, Cooper and Schrieffer (BCS) equations to construct the free quasi-particle sector of the Hamiltonian. The residual two-quasi-particle terms have been treated by applying the Tamm–Dancoff approximation (TDA) and random-phase approximation (RPA), suited to the extended neutrino media. With this, we have constructed neutrino energy distributions both in the superfluid and normal regimes and extracted critical values of the density and temperature.

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