Realistic inversion of diffraction data for an amorphous solid: The case of amorphous silicon

Pandey, Anup; Biswas, Parthapratim; Bhattarai, Bishal; Drabold, D. A.

doi:10.1103/physrevb.94.235208

Cited by 24 publications

(19 citation statements)

References 49 publications

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“…Recently, Drabold et al introduced a new "information-driven" paradigm, wherein the knowledge of both experimental constraints and the interatomic forcefield is simultaneously leveraged to produce realistic atomic models of glasses [26]. Specially, Drabold et al proposed a force-enhanced atomic refinement (FEAR) method, which relies on an iterative combination of RMC refinements (i.e., based on available experimental constraints) and energy minimizations (i.e., based on the knowledge of the interatomic forcefield) [7,26,27]. Unlike alternative hybrid RMC approaches-wherein both structure and energy are optimized simultaneously-the interatomic forces are here only computed during the energy minimization steps, which results in an improved overall computational efficiency [26].…”

Section: Introductionmentioning

confidence: 99%

New insights into the structure of sodium silicate glasses by force-enhanced atomic refinement

Zhou¹,

Du²,

Guo³

et al. 2020

Journal of Non-Crystalline Solids

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Although experiments can offer some fingerprints of the atomic structure of glasses (coordination numbers, pair distribution function, etc.), atomistic simulations are often required to directly access the structure itself (i.e., the positions of the atoms). On the one hand, molecular dynamics (MD) simulations can be used to generate by quenching a liquid-but MD simulations remain plagued by extremely high cooling rates. On the other hand, reverse Monte Carlo (RMC) modeling bypasses the melt-quenching route-but RMC often yields non-unique glass structures. Here, we adopt the force-enhanced atomic refinement (FEAR) method to overcome these limitations and decipher the atomic structure of a sodium silicate glass. We show that FEAR offers an unprecedented description of the atomic structure of sodium silicate. The FEAR-generated glass structure simultaneously exhibits (i) enhanced agreement with experimental neutron diffraction data and (ii) higher energetic stability as compared to those generated by MD or RMC. This result allows us to reveal new insights into the atomic structure of sodium silicate glasses. Specifically, we show that sodium silicate glasses exhibit a more ordered medium-range order structure than previously suggested by MD simulations. These results pave the way toward an increased ability to accurately describe the atomic structure of glasses.

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Section: Introductionmentioning

confidence: 99%

New insights into the structure of sodium silicate glasses by force-enhanced atomic refinement

Zhou¹,

Du²,

Guo³

et al. 2020

Journal of Non-Crystalline Solids

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“…chemical calculations can also be extremely valuable in their own right, as they intrinsically incorporate accurate information about the higher order interactions in materials. These calculations remain very computationally intensive for the large system sizes needed to accurately describe amorphous materials, although recent work has shown that an approach combining RMC refinement with ab initio relaxation can overcome the configurational barriers to reorganisation that have limited the application of quantum chemical calculations thus far, resulting in much more realistic models of amorphous materials 18,19 .…”

Section: Introductionmentioning

confidence: 99%

Structural simplicity as a restraint on the structure of amorphous silicon

et al. 2017

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Understanding the structural origins of the properties of amorphous materials remains one of the most important challenges in structural science. In this study we demonstrate that local 'structural simplicity', embodied by the degree to which atomic environments within a material are similar to each other, is powerful concept for rationalising the structure of canonical amorphous material amorphous silicon (a-Si). We show, by restraining a reverse Monte Carlo refinement against pair distribution function (PDF) data to be simpler, that the simplest model consistent with the PDF is a continuous random network (CRN). A further effect of producing a simple model of a-Si is the generation of a (pseudo)gap in the electronic density of states, suggesting that structural homogeneity drives electronic homogeneity. That this method produces models of a-Si that approach the state-of-the-art without the need for chemically specific restraints (beyond the assumption of homogeneity) suggests that simplicity-based refinement approaches may allow experiment-driven structural modelling techniques to be developed for the wide variety of amorphous semiconductors with strong local order. arXiv:1609.00668v3 [cond-mat.mtrl-sci]

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“…In the case of WWW and BM models, all the atoms in the generated samples are four-fold coordinated. This percentage is reduced to 88 − 90% in conventional RMC models [25,40], while it was increased to 96 − 99% in improved RMC models [26][27][28]. The percentage of fourfold-coordinated atoms is unrealistic for some RMC models [28,41] and the paracrystalline models analyzed [43].…”

Section: Resultsmentioning

confidence: 95%

“…The inherent variability of the a-Si configuration and properties depending on the fabrication process make the proper modeling of its structure difficult. An adequate understanding of the amorphous structure is needed, and recent studies demonstrate the interest in providing realistic atomistic models of amorphous solids that reproduce the structure of experimental samples [25][26][27][28][29]. a-Si has been considered as a prototype for tetrahedrally coordinated covalent amorphous materials, which can be described as a continuous random network (CRN) [6,30].…”

Section: Introductionmentioning

confidence: 99%

“…Initial RMC algorithms resulted in quite unrealistic bond angle distributions, large bond angle deviations, and large concentration of coordination defects [25,28,38]. More recently, RMC algorithms have been improved by including interatomic forces from empirical potentials or ab initio calculations in the fitting procedure that lead to more realistic atomistic models [25][26][27][28]41].…”

Section: Introductionmentioning

confidence: 99%

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Generation of amorphous Si structurally compatible with experimental samples through the quenching process: A systematic molecular dynamics simulation study

Santos

Aboy

Marqués

et al. 2019

Journal of Non-Crystalline Solids

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The construction of realistic atomistic models for amorphous solids is complicated by the fact that they do not have a unique structure. Among the different computational procedures available for this purpose, the melting and rapid quenching process using molecular dynamics simulations is commonly employed as it is simple and physically based. Nevertheless, the cooling rate used during quenching strongly affects the reliability of generated samples, as fast cooling rates result in unrealistic atomistic models. In this study, we have determined the conditions to be fulfilled when simulating the quenching process with molecular dynamics for obtaining amorphous Si (a-Si) atomistic models structurally compatible with experimental samples. We have analyzed the structure of samples generated with cooling rates ranging from 3.3 10 10 to 8.5 10 14 K/s. The obtained results were compared with experimental data available in the literature, and with samples generated by other state-of-the-art and more sophisticated computational procedures. For cooling rates below 10 11 K/s, a-Si samples generated had structural parameters within the range of experimental samples, and comparable to those obtained from other refined modeling procedures. These computationally slow cooling rates are of the same order of magnitude than those experimentally achieved with pulsed energy melting techniques. Samples obtained with faster cooling rates can be further relaxed with annealing simulations, resulting in structural parameters within the range of experimental samples. Nevertheless, the required annealing times are on the order of microseconds, which makes this annealing step non practical from a computational point of view.

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Realistic inversion of diffraction data for an amorphous solid: The case of amorphous silicon

Cited by 24 publications

References 49 publications

New insights into the structure of sodium silicate glasses by force-enhanced atomic refinement

New insights into the structure of sodium silicate glasses by force-enhanced atomic refinement

Structural simplicity as a restraint on the structure of amorphous silicon

Generation of amorphous Si structurally compatible with experimental samples through the quenching process: A systematic molecular dynamics simulation study

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