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Baldwin WJ, Liang X, Klarbring J, Dubajic M, Dell'Angelo D, Sutton C, Caddeo C, Stranks SD, Mattoni A, Walsh A, Csányi G. Dynamic Local Structure in Caesium Lead Iodide: Spatial Correlation and Transient Domains. Small 2024; 20:e2303565. [PMID: 37736694 DOI: 10.1002/smll.202303565] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/31/2023] [Indexed: 09/23/2023]
Abstract
Metal halide perovskites are multifunctional semiconductors with tunable structures and properties. They are highly dynamic crystals with complex octahedral tilting patterns and strongly anharmonic atomic behavior. In the higher temperature, higher symmetry phases of these materials, several complex structural features are observed. The local structure can differ greatly from the average structure and there is evidence that dynamic 2D structures of correlated octahedral motion form. An understanding of the underlying complex atomistic dynamics is, however, still lacking. In this work, the local structure of the inorganic perovskite CsPbI3 is investigated using a new machine learning force field based on the atomic cluster expansion framework. Through analysis of the temporal and spatial correlation observed during large-scale simulations, it is revealed that the low frequency motion of octahedral tilts implies a double-well effective potential landscape, even well into the cubic phase. Moreover, dynamic local regions of lower symmetry are present within both higher symmetry phases. These regions are planar and the length and timescales of the motion are reported. Finally, the spatial arrangement of these features and their interactions are investigated and visualized, providing a comprehensive picture of local structure in the higher symmetry phases.
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Affiliation(s)
- William J Baldwin
- Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK
| | - Xia Liang
- Department of Materials, Imperial College London, London, SW7 2AZ, UK
| | - Johan Klarbring
- Department of Materials, Imperial College London, London, SW7 2AZ, UK
- Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-581 83, Sweden
| | - Milos Dubajic
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | | | - Christopher Sutton
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29208, USA
| | - Claudia Caddeo
- CNR-IOM, Unitá di Cagliari, Monserrato, Caligari, 09042, Italy
| | - Samuel D Stranks
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK
| | | | - Aron Walsh
- Department of Materials, Imperial College London, London, SW7 2AZ, UK
| | - Gábor Csányi
- Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK
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Witt WC, van der Oord C, Gelžinytė E, Järvinen T, Ross A, Darby JP, Ho CH, Baldwin WJ, Sachs M, Kermode J, Bernstein N, Csányi G, Ortner C. ACEpotentials.jl: A Julia implementation of the atomic cluster expansion. J Chem Phys 2023; 159:164101. [PMID: 37870138 DOI: 10.1063/5.0158783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 08/25/2023] [Indexed: 10/24/2023] Open
Abstract
We introduce ACEpotentials.jl, a Julia-language software package that constructs interatomic potentials from quantum mechanical reference data using the Atomic Cluster Expansion [R. Drautz, Phys. Rev. B 99, 014104 (2019)]. As the latter provides a complete description of atomic environments, including invariance to overall translation and rotation as well as permutation of like atoms, the resulting potentials are systematically improvable and data efficient. Furthermore, the descriptor's expressiveness enables use of a linear model, facilitating rapid evaluation and straightforward application of Bayesian techniques for active learning. We summarize the capabilities of ACEpotentials.jl and demonstrate its strengths (simplicity, interpretability, robustness, performance) on a selection of prototypical atomistic modelling workflows.
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Affiliation(s)
- William C Witt
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom
| | - Cas van der Oord
- Engineering Laboratory, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Elena Gelžinytė
- Engineering Laboratory, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Teemu Järvinen
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia V6T 1Z2, Canada
| | - Andres Ross
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia V6T 1Z2, Canada
| | - James P Darby
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Cheuk Hin Ho
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia V6T 1Z2, Canada
| | - William J Baldwin
- Engineering Laboratory, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Matthias Sachs
- School of Mathematics, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - James Kermode
- Warwick Centre for Predictive Modelling, School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Noam Bernstein
- Center for Materials Physics and Technology, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA
| | - Gábor Csányi
- Engineering Laboratory, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Christoph Ortner
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia V6T 1Z2, Canada
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Liang X, Klarbring J, Baldwin WJ, Li Z, Csányi G, Walsh A. Structural Dynamics Descriptors for Metal Halide Perovskites. J Phys Chem C Nanomater Interfaces 2023; 127:19141-19151. [PMID: 37791100 PMCID: PMC10544022 DOI: 10.1021/acs.jpcc.3c03377] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 08/03/2023] [Indexed: 10/05/2023]
Abstract
Metal halide perovskites have shown extraordinary performance in solar energy conversion technologies. They have been classified as "soft semiconductors" due to their flexible corner-sharing octahedral networks and polymorphous nature. Understanding the local and average structures continues to be challenging for both modeling and experiments. Here, we report the quantitative analysis of structural dynamics in time and space from molecular dynamics simulations of perovskite crystals. The compact descriptors provided cover a wide variety of structural properties, including octahedral tilting and distortion, local lattice parameters, molecular orientations, as well as their spatial correlation. To validate our methods, we have trained a machine learning force field (MLFF) for methylammonium lead bromide (CH3NH3PbBr3) using an on-the-fly training approach with Gaussian process regression. The known stable phases are reproduced, and we find an additional symmetry-breaking effect in the cubic and tetragonal phases close to the phase-transition temperature. To test the implementation for large trajectories, we also apply it to 69,120 atom simulations for CsPbI3 based on an MLFF developed using the atomic cluster expansion formalism. The structural dynamics descriptors and Python toolkit are general to perovskites and readily transferable to more complex compositions.
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Affiliation(s)
- Xia Liang
- Department
of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
| | - Johan Klarbring
- Department
of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
- Department
of Physics, Chemistry and Biology (IFM), Linköping University, Linköping SE-581 83, Sweden
| | - William J. Baldwin
- Department
of Engineering, University of Cambridge, Cambridge CB2 1PZ, U.K.
| | - Zhenzhu Li
- Department
of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
| | - Gábor Csányi
- Department
of Engineering, University of Cambridge, Cambridge CB2 1PZ, U.K.
| | - Aron Walsh
- Department
of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
- Department
of Physics, Ewha Womans University, Seoul 03760, Korea
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