EXAFS study of hydrogen intercalation into ReO<sub>3</sub>using the evolutionary algorithm

Timoshenko, Janis; Kuzmin, Alexei; Purans, J.

doi:10.1088/0953-8984/26/5/055401

Cited by 105 publications

(190 citation statements)

References 62 publications

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“…Detailed description of our RMC/EA scheme is given in [6]. RMC/EA calculations were performed using a 4×4×4 supercell (256 atoms).…”

Section: Experimental and Simulation Detailsmentioning

confidence: 99%

“…As a consequence, the information amount, obtainable from EXAFS spectrum, again, is rather limited. In the presented study we treat this problem and complement the conventional RMC scheme with (i) a powerful evolutionary algorithm (EA) for efficient structure model optimization [6] and (ii) the use of wavelet transform (WT) [7], which allows us to represent EXAFS spectra in real and frequency spaces simultaneously and, hence, to obtain more information from the same experimental data [8]. This advanced approach allows us to probe more distant coordination shells and to reveal the anisotropy and correlations of atom thermal motion and static displacements.…”

Section: Introductionmentioning

confidence: 99%

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Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO₃lattice

Timoshenko

Kuzmin

Purans

2016

J. Phys.: Conf. Ser.

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Abstract. The influence of hydrogen intercalation on the local structure of rhenium trioxide is studied in-situ by the Re L3-edge EXAFS spectroscopy and analysed using a novel approach, based on the use of evolutionary algorithm and wavelet transform. The proposed method allows us to perform accurate EXAFS analysis within the multiple-scattering approach taking into account contributions from outer coordination shells and to access the information on correlations in atomic thermal motion. IntroductionThe analysis of extended X-ray absorption fine structure (EXAFS) data from the first coordination shell around the absorbing atom is nowadays a common tool to study the local structure of materials [1]. At the same time, EXAFS spectra, acquired at modern brilliant Xray sources, often contain much more information, especially for crystalline materials, where a contribution of distant coordination shells (up to 10Å and more) is frequently present in the total EXAFS spectrum. The precise analysis of EXAFS spectra beyond the first coordination shell using conventional methods is, however, often impossible since the contributions of outer shells overlap, and the total number of parameters, required to describe the local structure, growths exponentially with the increase of the number of coordination shells, included in the analysis [2]. Moreover, conventional EXAFS analysis even for the first coordination shell can be imprecise for significantly distorted or disordered systems, where the distributions of interatomic distances are often far from the Gaussian one [3].This problem may be treated by applying simulation-based techniques as molecular dynamics (MD) [3,4] and reverse Monte Carlo (RMC) method [5]. For our purposes the latter is especially interesting, since the RMC method does not require the knowledge and calculation of interatomic forces and relies solely on the available experimental EXAFS data. In RMC approach a 3D structure model of the material is constructed using an iterative random process, aimed to minimize the difference between experimental EXAFS and configuration-averaged EXAFS spectra, calculated for the given structure model. Once a good agreement between simulated and experimental spectra is obtained, one may expect that also the constructed model provides a good approximation of the material structure. The existing RMC implementations for EXAFS analysis, however, usually neglect the influence of multiple-scattering (MS) effects or treat them in an approximate way due to concomitant significant computational costs. As a consequence, the information amount, obtainable from EXAFS spectrum, again, is rather limited.

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“…Detailed description of our RMC/EA scheme is given in [6]. RMC/EA calculations were performed using a 4×4×4 supercell (256 atoms).…”

Section: Experimental and Simulation Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO₃lattice

Timoshenko

Kuzmin

Purans

2016

J. Phys.: Conf. Ser.

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“…Also, opposite to classical molecular dynamics, the RMC method is applicable at low temperatures. We have followed the procedure, described in [40], but the conventional RMC scheme [57] has been modified using the evolutionary algorithm (EA) [41]. Now instead of just one atomic configuration several supercells are modeled simultaneously.…”

Section: Rmc/ea-exafs Calculationsmentioning

confidence: 99%

“…Two techniques, classical molecular dynamics (MD) [39] and reverse Monte Carlo method coupled with evolutionary algorithm (RMC/EA) [40,41], have been employed for the interpretation of EXAFS spectra with the goals (i) to advance the understanding of the local atomic structure and dynamics of ZnO lattice and (ii) to validate existing force-field models [42,43,44] commonly used in MD simulations. Note that preliminary room temperature results have been presented by us recently in [45].…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the local structure and lattice dynamics of wurtzite-type ZnO

et al. 2014

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Temperature-dependent (10-300 K) Zn K-edge EXAFS spectra for polycrystalline wurtzite-type ZnO were analysed using ab initio multiple-scattering theory and taking into account anisotropy of the crystallographic structure and thermal disorder. We employed two different simulation approaches: classical molecular dynamics (MD) and reverse Monte Carlo coupled with evolutionary algorithm (RMC/EA method). The accuracy of several forcefield models, which are commonly used in the MD simulations of bulk and nanostructured ZnO, was tested based on a comparison between the experimental and simulated Zn K-edge EXAFS spectra. It was found that available force-field models fail to describe accurately many-atom distribution functions. More accurate solution was obtained by the RMC/EA method, which allowed us also to resolve the non-equivalent groups of atoms in the first two coordination shells around absorbing Zn atom and to follow the changes of structural parameters with temperature variation. It was found that upon increasing temperature the structure of ZnO becomes more anisotropic due to the increase of internal parameter u of the oxygen Wyckoff position (2b) and related Zn 0 -O 2 distances.

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“…It was realised in a number of computer codes as RMCprofile [48], SpecSwap-RMC [49], RMC++ [50] and EvAX [51]. The method was successfully used by us in the analysis of several materials as perovskites [51,52,32], tungstates [53,54,33], ZnO [31] and Y 2 O 3 [34].…”

Section: Introductionmentioning

confidence: 99%

Advanced approach to the local structure reconstruction and theory validation on the example of the W L₃-edge extended x-ray absorption fine structure of tungsten

Jonane

Anspoks

Kuzmin

2018

Modelling Simul. Mater. Sci. Eng.

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Abstract. Atomistic simulations of the experimental W L 3 -edge extended X-ray absorption fine structure (EXAFS) of bcc tungsten at T = 300 K were performed using classical molecular dynamics (MD) and reverse Monte Carlo (RMC) methods. The MD-EXAFS method based on the results of MD simulations allowed us to access the structural information, encoded in EXAFS, beyond the first coordination shell and to validate the accuracy of two interaction potential models -the embedded atom model potential and the second nearest-neighbor modified embedded atom method potential. The RMC-EXAFS method was used for more elaborate analysis of the EXAFS data giving access to thermal disorder effects. The results of both methods suggest that the correlation in atomic motion in bcc tungsten becomes negligible above 8Å. This fact allowed us to use the EXAFS data to determine not only mean-square relative displacements of atomic W-W pair motion but also mean-square displacements of individual tungsten atoms, which are usually accessible from diffraction data only.

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EXAFS study of hydrogen intercalation into ReO₃using the evolutionary algorithm

Cited by 105 publications

References 62 publications

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO₃lattice

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO₃lattice

Temperature dependence of the local structure and lattice dynamics of wurtzite-type ZnO

Advanced approach to the local structure reconstruction and theory validation on the example of the W L₃-edge extended x-ray absorption fine structure of tungsten

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EXAFS study of hydrogen intercalation into ReO3using the evolutionary algorithm

Cited by 105 publications

References 62 publications

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO3lattice

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO3lattice

Temperature dependence of the local structure and lattice dynamics of wurtzite-type ZnO

Advanced approach to the local structure reconstruction and theory validation on the example of the W L3-edge extended x-ray absorption fine structure of tungsten

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EXAFS study of hydrogen intercalation into ReO₃using the evolutionary algorithm

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO₃lattice

Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO₃lattice

Advanced approach to the local structure reconstruction and theory validation on the example of the W L₃-edge extended x-ray absorption fine structure of tungsten