<i>Ab initio</i>random structure searching

Pickard, Chris J.; Needs, R. J.

doi:10.1088/0953-8984/23/5/053201

Cited by 1,085 publications

(1,044 citation statements)

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“…These computational appraoches include evolutionary algorithms [30][31][32][33][34] , particle swarm optimization, 35 methods based on molecular dynamics, such as simulated annealing 36 , minima hopping, 37 and metadynamics 38 . Also a search approach based on the local energy minimization of randomly generated structures 39 has been successfully applied to numerous materials.…”

Section: Application Of the Global Space Group Optimization (Gsgomentioning

confidence: 99%

Emergence of a few distinct structures from a single formal structure type during high-throughput screening for stable compounds: The case of RbCuS and RbCuSe

et al. 2015

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Theoretical sorting of stable and synthesizable "missing compounds" from those that are unstable is a crucial step in the discovery of previously unknown functional materials. This active research area often involves high throughput (HT) examination of the total energy of a given compound in a list of candidate formal structure types (FSTs), searching for those with the lowest energy within that list. While it is well appreciated that local relaxation methods based on a fixed list of structure types can lead to inaccurate geometries, this approach is widely used in HT studies because it produces answers faster than global optimization methods (that vary lattice vectors and atomic positions without local restrictions). We find, however a different failure mode of the HT protocol: specific crystallographic classes of formal structure types correspond each to a series of chemically distinct "daughter structure types" (DSTs) that have the same space group, but posses totally different local bonding configurations, including coordination types.Failure to include such DSTs in the fixed list of examined candidate structures used in contemporary high throughput approaches can lead to qualitative misidentification of the stable bonding pattern, not just quantitative inaccuracies. In this work we (i) clarify the understanding of the general DST-FST relationship, thus improving current discovery HT approaches, (ii) illustrate this failure mode for RbCuS and RbCuSe (a newly predicted compound) by developing a synthesis method and accelerated crystal structure determination and, (iii) apply the genetic-algorithm based Global Space Group Optimization (GSGO) approach which is not vulnerable to the failure-mode of HT searches of fixed lists, demonstrating a correct identification of the stable DST. The broad impact of items (i)-(iii) lies in the demonstrated understanding of a new strategy-use HT as preliminary broad screening, followed by unbiased GSGO of the final candidates.2

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Section: Application Of the Global Space Group Optimization (Gsgomentioning

confidence: 99%

Emergence of a few distinct structures from a single formal structure type during high-throughput screening for stable compounds: The case of RbCuS and RbCuSe

et al. 2015

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“…Taken together, an arbitrarily large set of these cells provide a more complete description of the δ-hydride and a concentrated solid solution than any single periodic calculation. The advantages of random structure generation have been discussed previously 39 .…”

Section: Cell Configurationsmentioning

confidence: 99%

The thermodynamics of hydride precipitation: The importance of entropy, enthalpy and disorder

et al. 2014

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The thermodynamics of H/α-Zr solid solution and zirconium hydride phases were studied using density functional theory. Disorder in ζ, γ and δ hydrides and solid solutions were modelled using a statistically significant number of randomly generated structures in combination with special quasirandom structures and solid solutions with a range of concentrations. This is used in conjunction with a calculation of thermodynamic parameters of the system, including the temperature dependent sensible enthalpy, configurational entropy and vibrational entropy of the different crystals in the system, developed from phonon density of states. It was found that precipitation of hydrides is not thermodynamically favourable for Zr-H solid solutions containing less than 300 ppm H, suggesting that a mechanism must cause local concentration of H atoms to a greater amount than found globally in experimental samples containing hydrides. Temperature drives the reaction in the direction of solution, primarily due to entropic effects. Generally, γ hydride is the most stable phase, although it is very close in energy to the δ-phase. The sensible enthalpy of precipitation assists in stabilising HCP hydrides, and the configurational entropy change during precipitation favours FCC hydrides. None of the thermodynamic contributions are found to be negligible in driving precipitation.arXiv:1401.5637v1 [cond-mat.mtrl-sci] 22 Jan 2014 2

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“…This explains the failure of earlier theoretical calculations 7,8 by assuming that the structures of compounds resemble those in pure metals. Our findings were benefited from the unbiased structure prediction techniques 18,19,26,27 Table S1). The convex hull calculations (Fig.…”

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confidence: 99%