Theoretical simulation of V<sub>K</sub>-centre migration in KCl. I. A quantum-chemical study

Shluger, Alexander L.; Kantorovich, Lev; Heifets, E.; Shidlovskaya, E K; Grimes, Robin W.

doi:10.1088/0953-8984/4/36/015

Cited by 25 publications

(10 citation statements)

References 40 publications

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“…It was similarly shown that 60 • /120 • rotations dominate in RbI. 31,32 Table I shows activation barriers calculated within the pSIC-PBE and optimized hybrid approaches using the climbing image nudged elastic band method. 33 Both methods agree very well with each other and with experimental data.…”

Section: B Vk -Center Migration In Naimentioning

confidence: 98%

Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

Sadigh¹,

Erhart²,

Åberg³

2015

Phys. Rev. B

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We conduct a detailed investigation of the polaron self-interaction (pSI) error in standard approximations to the exchange-correlation (XC) functional within density-functional theory (DFT). The pSI leads to delocalization error in the polaron wave function and energy, as calculated from the Kohn-Sham (KS) potential in the native charge state of the polaron. This constitutes the origin of the systematic failure of DFT to describe polaron formation in band insulators. It is shown that the delocalization error in these systems is, however, largely absent in the KS potential of the closed-shell neutral charge state. This leads to a modification of the DFT total-energy functional that corrects the pSI in the XC functional. The resulting pSIC-DFT method constitutes an accurate parameter-free ab initio methodology for calculating polaron properties in insulators at a computational cost that is orders of magnitude smaller than hybrid XC functionals. Unlike approaches that rely on parametrized localized potentials such as DFT+U , the pSIC-DFT method properly captures both site and bond-centered polaron configurations. This is demonstrated by studying formation and migration of self-trapped holes in alkali halides (bond-centered) as well as self-trapped electrons in an elpasolite compound (site-centered). The pSIC-DFT approach consistently reproduces the results obtained by hybrid XC functionals parametrized by DFT+G0W0 calculations. Finally, we generalize the pSIC approach to hybrid functionals, and show that in stark contrast to conventional hybrid calculations of polaron energies, the pSIC-hybrid method is insensitive to the parametrization of the hybrid XC functional. On this basis, we further rationalize the success of the pSIC-DFT approach.

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Section: B Vk -Center Migration In Naimentioning

confidence: 98%

Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

Sadigh¹,

Erhart²,

Åberg³

2015

Phys. Rev. B

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“…There are predictions of formation energies, optical transition energies, Arrhenius energies for the several different incoherent hopping transitions, the dipole tensor, the spin resonance hyperfine constants, and so on (Tasker and Stoneham 1977, Norgett and Stoneham 1973a, 1973b. Shluger et al (1992) have developed the theory for the 60 • reorientations of V k centres in alkali halides. Several points must be made.…”

Section: Halides: V K Centres and Tests Of Ideasmentioning

confidence: 99%

Trapping, self-trapping and the polaron family

Stoneham

Gavartin

Shluger

et al. 2007

J. Phys.: Condens. Matter

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214

190

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The earliest ideas of the polaron recognized that the coupling of an electron to ionic vibrations would affect its apparent mass and could effectively immobilize the carrier (self-trapping). We discuss how these basic ideas have been generalized to recognize new materials and new phenomena. First, there is an interplay between self-trapping and trapping associated with defects or with fluctuations in an amorphous solid. In high dielectric constant oxides, like HfO 2 , this leads to oxygen vacancies having as many as five charge states. In colossal magnetoresistance manganites, this interplay makes possible the scanning tunnelling microscopy (STM) observation of polarons. Second, excitons can self-trap and, by doing so, localize energy in ways that can modify the material properties. Third, new materials introduce new features, with polaron-related ideas emerging for uranium dioxide, gate dielectric oxides, Jahn-Teller systems, semiconducting polymers and biological systems. The phonon modes that initiate self-trapping can be quite different from the longitudinal optic modes usually assumed to dominate. Fourth, there are new phenomena, like possible magnetism in simple oxides, or with the evolution of short-lived polarons, like muons or excitons. The central idea remains that of a particle whose properties are modified by polarizing or deforming its host solid, sometimes profoundly. However, some of the simpler standard assumptions can give a limited, indeed misleading, description of real systems, with qualitative inconsistencies. We discuss representative cases for which theory and experiment can be compared in detail.

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“…The model and the geometric structure of the V k -center in alkali halides has been first proposed on the basis of the analysis of the electron spin resonance data 21,22 and later refined in numerous theoretical calculations 17,23,24,25 . The structure and stability of the V k -center is primarily determined by the chemical bond formation between the two halogen ions, assisted by the lattice polarization.…”

Section: Self-trapped Exciton and Hole In Alkali Halides: Backgroundmentioning

confidence: 99%

Modeling charge self-trapping in wide-gap dielectrics: Localization problem in local density functionals

2003

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We discuss the adiabatic self-trapping of small polarons within the density functional theory (DFT). In particular, we carried out plane-wave pseudo-potential calculations of the triplet exciton in NaCl and found no energy minimum corresponding to the self-trapped exciton (STE) contrary to the experimental evidence and previous calculations. To explore the origin of this problem we modelled the self-trapped hole in NaCl using hybrid density functionals and an embedded cluster method. Calculations show that the stability of the self-trapped state of the hole drastically depends on the amount of the exact exchange in the density functional: at less than 30% of the Hartree-Fock exchange, only delocalized hole is stable, at 50% -both delocalized and self-trapped states are stable, while further increase of exact exchange results in only the self-trapped state being stable. We argue that the main contributions to the self-trapping energy such as the kinetic energy of the localizing charge, the chemical bond formation of the di-halogen quasi molecule, and the lattice polarization, are represented incorrectly within the Kohn-Sham (KS) based approaches.

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Theoretical simulation of V_K-centre migration in KCl. I. A quantum-chemical study

Cited by 25 publications

References 40 publications

Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

Trapping, self-trapping and the polaron family

Modeling charge self-trapping in wide-gap dielectrics: Localization problem in local density functionals

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Theoretical simulation of VK-centre migration in KCl. I. A quantum-chemical study

Cited by 25 publications

References 40 publications

Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

Variational polaron self-interaction-corrected total-energy functional for charge excitations in insulators

Trapping, self-trapping and the polaron family

Modeling charge self-trapping in wide-gap dielectrics: Localization problem in local density functionals

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Theoretical simulation of V_K-centre migration in KCl. I. A quantum-chemical study