Drude-like model

The temperature dependence of the IR refiectivity spectra of the Lii oTij 005S2 sample is similar to those of the pure material. The spectra show a dip close to the plasma frequency p = 4180 cm extracted from analysis of the data using a Drude-like model with a frequency dependent relaxation time, as ... 

Theoretical modelling shows that this configuration is more favourable for the achievement of a full photonic band-gap, provided that there is a dielectric contrast of at least 2.8 [30]. This requirement is hard to achieve, and it has only been reported for silicon [31] and germanium [32] inverse opals. An alternative can be the use of metals with a Drude-like behavior of the dielectric function. When the dielectric contrast of the photonic crystal becomes extremely... 

The Drude oscillator model has a number of advantages over other polarizable models facilitating its implementation in multiple simulation packages including CHARMM [150], NAMD [165], ChemSell QM/MM [192] and the OpenMM suite of utilities for GPU [193]. Representing a dipole as two point charges provides an intuitive physical picture in terms of displacement of the electronic distribution the model is able to represent delocalization without need of additional non-atomic sites since the dipole is not point-like as, e.g., in the induced dipole model. For example, the use of auxiliary particles allows for the inclusion of mechanical polarizabilities [194]... 

Fig. 3. The < tical conductivity calculated within a one-band Hubbard model on a 4x4 cluster (Dagotto 1994). Parameter x stands for the hole-doping fraction. Calculations reproduce the principal trends of the experimental data on the evolution of the electromagnetic response with doping. In particular, theoretical spectra reveal (i) the transfer of the spectral weight from the CT excitation to the iow-ftequency region (ii) development of mid-infiared absorption at light doping (x = 0.125) and (iii) growth of the Drude-like feature at higher dopings (x > 0.2). Note that the isobestic point at m/t = 5 is also reproduced.

Although the overall low-frequenspectral response of all metallic conducting polymers, such as PANI-CSA, PPy-PF6, and PEDOT-PFg, can be attributed to free-carrier intraband excitations, their o like behavior below 0.2 eV [1160-1165]. The anomalous behavior of a(o)) and ei(oj) in the low energies (typically below 0.2-0.4 eV) can be attributed to disorder-induced localization, and can be analyzed in terms of the localization-modified Drude (LMD) model [1160-1165], This LMD model, originally proposed by Mott and co-workers [1125, 1156, 1157], has been modified by Lee et al. [1160] and successfully introduced into the analysis of optical spectra of metallic conducting polymers [1160-1165]. This model is a first-order correction of the Drude model in the regime of weak localization, as given by [1160]... 

At large doping values, i.e., for the highest T<- values, the mid-IR and Drude-like responses of the high Tc cuprates eventually merge into what appears to be a single Drude-like response (Fig. 4b). Under the assumption that this response is comprised of only a single-component response, an extended Drude model is necessary to fit the data. This assumption, in turn, leads to the conclusion that the carrier mass is frequency-dependent, and that the carrier... 

The permittivity of metals is usually modeled using a Drude-like function of the form ... 

After the pioneering quantum mechanical work not much new ground was broken until computers and software had matured enough to try fresh attacks. In the meantime the study of intermolecular forces was mainly pursued by thermodynamicists who fitted model potentials, often of the Lennard-Jones form [10] 4e[(cr/R) — (cr// ) ], to quantities like second virial coefficients, viscosity and diffusion coefficients, etc. Much of this work is described in the authoritative monograph of Hirschfelder et al. [11] who, incidentally, also gave a good account of the relationship of Drude s classical work to that of London. 

Despite of its simplicity the Drude model correctly describes the optical properties of simple metals. In Fig. 1.4 we report the experimental dielectric constant, the refractive index and the reflectance for aluminum. Figure 1.4 closely resembles Fig. 1.3 with (Op 15 eV. The best agreement of the dielectric function of metal with that obtained in the framework of the free electron model can be obtained for the alkali metals (Li, Na, K, Cs, Rb), whose response seems to be weakly affected by the contribution from the core electrons. Notably, alkali metals, such as sodium, have an almost free-electron-like response and thus, in accordance... 

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