Polarization-based calculation of the dielectric tensor of polar crystals (original) (raw)
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Physical Review B, 1998
We discuss a non-perturbative, technically straightforward, easy-to-use, and computationally affordable method, based on polarization theory, for the calculation of the electronic dielectric constant of insulating solids at the first principles level. We apply the method to GaAs, AlAs, InN, SiC, ZnO, GaN, AlN, BeO, LiF, PbTiO3, and CaTiO3. The predicted ε ∞ 's agree well with those given by Density Functional Perturbation Theory (the reference theoretical treatment), and they are generally within less than 10 % of experiment. 77.22.Ej,77.22.Ch,77.84.Bw,77.84.Dy
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We describe a method to calculate the electronic properties of an insulator under an applied electric field. It is based on the minimization of an electric enthalpy functional with respect to the orbitals, which behave as Wannier functions under crystal translations, but are not necessarily orthogonal. This paper extends the approach of Nunes and Vanderbilt (NV) [Phys. Rev. Lett. 73, 712 (1994)], who demonstrated that a Wannier function representation can be used to study insulating crystals in the presence of a finite electric field. According to a study by Fernandez et al. [Phys. Rev. B. 58, R7480 (1998)], first-principles implementations of the NV approach suffer from the impact of the localization constraint on the orthogonal wave functions, what affects the accuracy of the physical results. We show that because non-orthogonal generalized Wannier functions can be more localized than their orthogonal counterparts, the error due to localization constraints is reduced, thus improvi...
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Arxiv preprint cond-mat/0011243, 2000
We demonstrate that polarization-related quantities in semiconductors can be predicted accurately from first-principles calculations using the appropriate approach to the problem, the Berryphase polarization theory. For III-V nitrides, our test case, we find polarizations, polarization differences between nitride pairs, and piezoelectric constants quite close to their previously established values. Refined data are nevertheless provided for all the relevant quantities.
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The spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry phase approach to polarization in solids. The piezoelectric constants are found to be up 10 times larger than in conventional III-V's and II-VI's, and comparable to those of ZnO. Further properties at variance with those of conventional III-V compounds are the sign of the piezoelectric constants (positive as in II-VI's) and the very large spontaneous polarization.
dmzbs electronic polarization JCTC_2014.pdf
Static dielectric tensors and charge carrier polarization energies of a wide set of organic molecules of interest for organic electronics application are calculated with two different approaches: intramolecular charge redistribution and induced dipoles (microlectrostatics). Our results show that, while charge redistribution is better suited for calculating the collective response to an external field, both methods reliably describe the effect of a localized charge carrier in the crystal. Advantages and limitations inherent to the different methods are discussed, also in relation to previous theoretical studies. The agreement with available experimental data confers to our results a predictive character where measurements are missing.
Pyroelectricity with an extra-polarization effect in AlN/GaN heterostructures
The twin members, AlN and GaN of group-III nitrides (AlN, GaN and InN) possess strong built-inpolarization effect. This polarization effect can additionally influence certain parameters of pyroelectricity and hence can be defined as an extra-polarization effect P. AlN and GaN being the pyroelectrics the polarization effect is inherent phenomenon in these materials. For this reason the epitaxially grown AlN/GaN heterostructures on suitable substrate have diverse applications in the field of nanostructure electronics and optoelectronics device. The extra-polarization effect and pyroelectricity in AlN and GaN are highly z-axis oriented which can also be changed by putting under strain. However, the entire mechanism of pyroelectric effect in AlN/GaN heterostructures has not been explored so far. In this context we discuss the extra-polarization effect P which additionally influence the pyroelectric parameters of AlN/ GaN heterostructures and theoretically calculate its effect on pyroelectricity of the heterostructures. The total pyroelectric coefficients at room temperature is foundÀ1:65lCm À2 K À1 in AlN/GaN heterostructure when with extra-polarization effect is accounted. The present study advocates that the pyroelectric measurement can reveal the interplay of both acoustic and optical phonons in the pyroelectricity of AlN/ GaN heterostructures. Hence the polarization property can be important for the sensor device design.
Polarons in wurtzite nitride semiconductors
Solid State Communications, 1999
Polaron binding energy and effective mass are calculated for semiconductors with wurtzite crystalline structure from the first order electron-phonon corrections to the self-energy. A recently introduced Fröhlich-like electron-phonon interaction Hamiltonian which accounts for the LO and TO polarizations mixing due to the anisotropy is used in the calculation. The polaronic damping rates are evaluated for finite temperature. Numerical results are reported for GaN. It is shown that the electron-phonon coupling is strong enough to justify the necessity of the inclusion of second-order corrections.