First-Principles Calculation of Defect Properties on Copper Doped KTaO3 Crystal
01 Jan 2021-ECS Journal of Solid State Science and Technology (The Electrochemical Society)-Vol. 10, Iss: 1, pp 014009
About: This article is published in ECS Journal of Solid State Science and Technology.The article was published on 2021-01-01. It has received 2 citations till now. The article focuses on the topics: Crystal & Copper.
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TL;DR: In this article, the effects of Sb3+, Nb3+ and V3+ atom doping on the ferroelectric dynamics of cubic KTaO3 induced by mid-infrared light through the nonlinear coupling of phonon modes were investigated.
Abstract: Strong mid-infrared pulses are used to directly control the dynamics of the crystal lattice. In this paper, we studied the effects of Sb3+, Nb3+ and V3+ atom doping on the ferroelectric dynamics of cubic KTaO3 induced by mid-infrared light through the nonlinear coupling of phonon modes. We found that Nb3+ and V3+ doping cause the coupling constant l between the highest (Qhx) and lowest frequency phonon mode (Qlz) to be negative, which results in a softening of the Qlz mode when the Qhx mode is externally pumped; Sb3+ doping will increase the damping effect and inhibit the occurrence of KTaO3 light-induced ferroelectricity; and it is proved that the two different configurations of doped KTaO3 compounds can suppress or enhance the photo-induced ferroelectricity of KTaO3. KTaO3-defect-1 doped with V3+ can cause the light-induced ferroelectricity of KTaO3, but KTaO3-defect-2 doped with V3+ inhibited it. In short, our research results strongly support the idea of using atomic doping to control the photo-induced ferroelectricity of KTaO3, which provides an effective strategy for using the light-induced ferroelectricity in all-optical devices.
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TL;DR: In this paper , the authors summarize the research progress of KTN series crystals systemically, including the theoretical exploration on quadratic EO effect, solid-melt crystal growth technique, comprehensive physical characterization, new physical effect and mechanisms exploration, new EO devices development and design.
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TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif
146,533 citations
TL;DR: An efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set is presented and the application of Pulay's DIIS method to the iterative diagonalization of large matrices will be discussed.
Abstract: We present an efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrices will be discussed. Our approach is stable, reliable, and minimizes the number of order ${\mathit{N}}_{\mathrm{atoms}}^{3}$ operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special ``metric'' and a special ``preconditioning'' optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calculations. It will be shown that the number of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order ${\mathit{N}}_{\mathrm{atoms}}^{2}$ scaling is found for systems containing up to 1000 electrons. If we take into account that the number of k points can be decreased linearly with the system size, the overall scaling can approach ${\mathit{N}}_{\mathrm{atoms}}$. We have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large number of different systems (liquid and amorphous semiconductors, liquid simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable. \textcopyright{} 1996 The American Physical Society.
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TL;DR: In this article, a method for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector is given, where the integration can be over the entire zone or over specified portions thereof.
Abstract: A method is given for generating sets of special points in the Brillouin zone which provides an efficient means of integrating periodic functions of the wave vector. The integration can be over the entire Brillouin zone or over specified portions thereof. This method also has applications in spectral and density-of-state calculations. The relationships to the Chadi-Cohen and Gilat-Raubenheimer methods are indicated.
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TL;DR: In this paper, the Hartree-Fock parallel spin probability was used to identify localized electronic groups in atomic and molecular systems, which is completely independent of unitary orbital transformations.
Abstract: We introduce in this work a new approach to the identification of localized electronic groups in atomic and molecular systems. Our approach is based on local behavior of the Hartree–Fock parallel‐spin pair probability and is completely independent of unitary orbital transformations. We derive a simple ‘‘electron localization function’’ (ELF) which easily reveals atomic shell structure and core, binding, and lone electron pairs in simple molecular systems as well.
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TL;DR: In this paper, the authors describe the state-of-the-art computational methodology for calculating the structure and energetics of point defects and impurities in semiconductors and pay particular attention to computational aspects which are unique to defects or impurities, such as how to deal with charge states and how to describe and interpret transition levels.
Abstract: First-principles calculations have evolved from mere aids in explaining and supporting experiments to powerful tools for predicting new materials and their properties. In the first part of this review we describe the state-of-the-art computational methodology for calculating the structure and energetics of point defects and impurities in semiconductors. We will pay particular attention to computational aspects which are unique to defects or impurities, such as how to deal with charge states and how to describe and interpret transition levels. In the second part of the review we will illustrate these capabilities with examples for defects and impurities in nitride semiconductors. Point defects have traditionally been considered to play a major role in wide-band-gap semiconductors, and first-principles calculations have been particularly helpful in elucidating the issues. Specifically, calculations have shown that the unintentional n-type conductivity that has often been observed in as-grown GaN cannot be a...
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