--- _id: '15052' abstract: - lang: eng text: "Substrate induces mechanical strain on perovskite devices, which can result in alterations to its lattice dynamics and thermal transport. Herein, we have performed a theoretical investigation on the anharmonic lattice dynamics and thermal property of perovskite Rb2SnBr6 and Cs2SnBr6 under strains using perturbation theory up to the fourth-order terms and the unified thermal transport theory. We demonstrate a pronounced hardening of low-frequency optical phonons as temperature increases, indicating strong lattice anharmonicity and the necessity of adopting temperature-dependent interatomic force constants in the lattice thermal conductivity (\r\nκL) calculations. It is found that the low-lying optical phonon modes of Rb2SnBr6 are extremely soft and their phonon energies are almost strain independent, which ultimately lead to a lower \r\nκL and a weaker strain dependence than Cs2SnBr6. We further reveal that the strain dependence of these phonon modes in the A2XB6-type perovskites weakens as their ibrational frequency decreases. This study deepens the understanding of lattice thermal transport in perovskites A2XB6 and provides a perspective on the selection of materials that meet the expected thermal behaviors in practical applications." acknowledgement: "This work is supported by the Research Grants Council of Hong Kong (C7002-22Y and 17318122). The authors are grateful for the research computing facilities offered by\r\nITS, HKU. Z.Z. acknowledges the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 101034413." article_number: '054305' article_processing_charge: No article_type: original author: - first_name: Ruihuan full_name: Cheng, Ruihuan last_name: Cheng - first_name: Zezhu full_name: Zeng, Zezhu id: 54a2c730-803f-11ed-ab7e-95b29d2680e7 last_name: Zeng - first_name: Chen full_name: Wang, Chen last_name: Wang - first_name: Niuchang full_name: Ouyang, Niuchang last_name: Ouyang - first_name: Yue full_name: Chen, Yue last_name: Chen citation: ama: Cheng R, Zeng Z, Wang C, Ouyang N, Chen Y. Impact of strain-insensitive low-frequency phonon modes on lattice thermal transport in AxXB6-type perovskites. Physical Review B. 2024;109(5). doi:10.1103/physrevb.109.054305 apa: Cheng, R., Zeng, Z., Wang, C., Ouyang, N., & Chen, Y. (2024). Impact of strain-insensitive low-frequency phonon modes on lattice thermal transport in AxXB6-type perovskites. Physical Review B. American Physical Society. https://doi.org/10.1103/physrevb.109.054305 chicago: Cheng, Ruihuan, Zezhu Zeng, Chen Wang, Niuchang Ouyang, and Yue Chen. “Impact of Strain-Insensitive Low-Frequency Phonon Modes on Lattice Thermal Transport in AxXB6-Type Perovskites.” Physical Review B. American Physical Society, 2024. https://doi.org/10.1103/physrevb.109.054305. ieee: R. Cheng, Z. Zeng, C. Wang, N. Ouyang, and Y. Chen, “Impact of strain-insensitive low-frequency phonon modes on lattice thermal transport in AxXB6-type perovskites,” Physical Review B, vol. 109, no. 5. American Physical Society, 2024. ista: Cheng R, Zeng Z, Wang C, Ouyang N, Chen Y. 2024. Impact of strain-insensitive low-frequency phonon modes on lattice thermal transport in AxXB6-type perovskites. Physical Review B. 109(5), 054305. mla: Cheng, Ruihuan, et al. “Impact of Strain-Insensitive Low-Frequency Phonon Modes on Lattice Thermal Transport in AxXB6-Type Perovskites.” Physical Review B, vol. 109, no. 5, 054305, American Physical Society, 2024, doi:10.1103/physrevb.109.054305. short: R. Cheng, Z. Zeng, C. Wang, N. Ouyang, Y. Chen, Physical Review B 109 (2024). date_created: 2024-03-04T07:41:23Z date_published: 2024-02-14T00:00:00Z date_updated: 2024-03-04T07:48:55Z day: '14' department: - _id: BiCh doi: 10.1103/physrevb.109.054305 ec_funded: 1 intvolume: ' 109' issue: '5' language: - iso: eng month: '02' oa_version: None project: - _id: fc2ed2f7-9c52-11eb-aca3-c01059dda49c call_identifier: H2020 grant_number: '101034413' name: 'IST-BRIDGE: International postdoctoral program' publication: Physical Review B publication_identifier: eissn: - 2469-9969 issn: - 2469-9950 publication_status: published publisher: American Physical Society quality_controlled: '1' scopus_import: '1' status: public title: Impact of strain-insensitive low-frequency phonon modes on lattice thermal transport in AxXB6-type perovskites type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 109 year: '2024' ... --- _id: '14425' abstract: - lang: eng text: 'Water adsorption and dissociation processes on pristine low-index TiO2 interfaces are important but poorly understood outside the well-studied anatase (101) and rutile (110). To understand these, we construct three sets of machine learning potentials that are simultaneously applicable to various TiO2 surfaces, based on three density-functional-theory approximations. Here we show the water dissociation free energies on seven pristine TiO2 surfaces, and predict that anatase (100), anatase (110), rutile (001), and rutile (011) favor water dissociation, anatase (101) and rutile (100) have mostly molecular adsorption, while the simulations of rutile (110) sensitively depend on the slab thickness and molecular adsorption is preferred with thick slabs. Moreover, using an automated algorithm, we reveal that these surfaces follow different types of atomistic mechanisms for proton transfer and water dissociation: one-step, two-step, or both. These mechanisms can be rationalized based on the arrangements of water molecules on the different surfaces. Our finding thus demonstrates that the different pristine TiO2 surfaces react with water in distinct ways, and cannot be represented using just the low-energy anatase (101) and rutile (110) surfaces.' acknowledgement: F.S., J.H., and B.C. thank the Swiss National Supercomputing Centre (CSCS) for the generous allocation of CPU hours via production project s1108 at the Piz Daint supercomputer. B.C. acknowledges resources provided by the Cambridge Tier-2 system operated by the University of Cambridge Research Computing Service funded by EPSRC Tier-2 capital grant EP/P020259/1. J.C. acknowledges the Beijing Natural Science Foundation for support under grant No. JQ22001. F.S., and J.H. thank the Swiss Platform for Advanced Scientific Computing (PASC) via the 2021-2024 “Ab Initio Molecular Dynamics at the Exa-Scale” project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 101034413. article_number: '6131' article_processing_charge: Yes article_type: original arxiv: 1 author: - first_name: Zezhu full_name: Zeng, Zezhu id: 54a2c730-803f-11ed-ab7e-95b29d2680e7 last_name: Zeng - first_name: Felix full_name: Wodaczek, Felix id: 8b4b6a9f-32b0-11ee-9fa8-bbe85e26258e last_name: Wodaczek orcid: 0009-0000-1457-795X - first_name: Keyang full_name: Liu, Keyang last_name: Liu - first_name: Frederick full_name: Stein, Frederick last_name: Stein - first_name: Jürg full_name: Hutter, Jürg last_name: Hutter - first_name: Ji full_name: Chen, Ji last_name: Chen - first_name: Bingqing full_name: Cheng, Bingqing id: cbe3cda4-d82c-11eb-8dc7-8ff94289fcc9 last_name: Cheng orcid: 0000-0002-3584-9632 citation: ama: Zeng Z, Wodaczek F, Liu K, et al. Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations. Nature Communications. 2023;14. doi:10.1038/s41467-023-41865-8 apa: Zeng, Z., Wodaczek, F., Liu, K., Stein, F., Hutter, J., Chen, J., & Cheng, B. (2023). Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations. Nature Communications. Springer Nature. https://doi.org/10.1038/s41467-023-41865-8 chicago: Zeng, Zezhu, Felix Wodaczek, Keyang Liu, Frederick Stein, Jürg Hutter, Ji Chen, and Bingqing Cheng. “Mechanistic Insight on Water Dissociation on Pristine Low-Index TiO2 Surfaces from Machine Learning Molecular Dynamics Simulations.” Nature Communications. Springer Nature, 2023. https://doi.org/10.1038/s41467-023-41865-8. ieee: Z. Zeng et al., “Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations,” Nature Communications, vol. 14. Springer Nature, 2023. ista: Zeng Z, Wodaczek F, Liu K, Stein F, Hutter J, Chen J, Cheng B. 2023. Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations. Nature Communications. 14, 6131. mla: Zeng, Zezhu, et al. “Mechanistic Insight on Water Dissociation on Pristine Low-Index TiO2 Surfaces from Machine Learning Molecular Dynamics Simulations.” Nature Communications, vol. 14, 6131, Springer Nature, 2023, doi:10.1038/s41467-023-41865-8. short: Z. Zeng, F. Wodaczek, K. Liu, F. Stein, J. Hutter, J. Chen, B. Cheng, Nature Communications 14 (2023). date_created: 2023-10-15T22:01:10Z date_published: 2023-10-02T00:00:00Z date_updated: 2023-12-13T13:02:07Z day: '02' ddc: - '540' - '000' department: - _id: BiCh - _id: GradSch doi: 10.1038/s41467-023-41865-8 ec_funded: 1 external_id: arxiv: - '2303.07433' isi: - '001084354900008' pmid: - '37783698' file: - access_level: open_access checksum: 7d1dffd36b672ec679f08f70ce79da87 content_type: application/pdf creator: dernst date_created: 2023-10-16T07:34:49Z date_updated: 2023-10-16T07:34:49Z file_id: '14432' file_name: 2023_NatureComm_Zeng.pdf file_size: 3194116 relation: main_file success: 1 file_date_updated: 2023-10-16T07:34:49Z has_accepted_license: '1' intvolume: ' 14' isi: 1 language: - iso: eng month: '10' oa: 1 oa_version: Published Version pmid: 1 project: - _id: fc2ed2f7-9c52-11eb-aca3-c01059dda49c call_identifier: H2020 grant_number: '101034413' name: 'IST-BRIDGE: International postdoctoral program' publication: Nature Communications publication_identifier: eissn: - 2041-1723 publication_status: published publisher: Springer Nature quality_controlled: '1' related_material: link: - relation: software url: https://github.com/BingqingCheng/TiO2-water scopus_import: '1' status: public title: Mechanistic insight on water dissociation on pristine low-index TiO2 surfaces from machine learning molecular dynamics simulations tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 14 year: '2023' ... --- _id: '14605' abstract: - lang: eng text: The phonon transport mechanisms and ultralow lattice thermal conductivities (κL) in silver halide AgX (X=Cl,Br,I) compounds are not yet well understood. Herein, we study the lattice dynamics and thermal property of AgX under the framework of perturbation theory and the two-channel Wigner thermal transport model based on accurate machine learning potentials. We find that an accurate extraction of the third-order atomic force constants from largely displaced configurations is significant for the calculation of the κL of AgX, and the coherence thermal transport is also non-negligible. In AgI, however, the calculated κL still considerably overestimates the experimental values even including four-phonon scatterings. Molecular dynamics (MD) simulations using machine learning potential suggest an important role of the higher-than-fourth-order lattice anharmonicity in the low-frequency phonon linewidths of AgI at room temperature, which can be related to the simultaneous restrictions of the three- and four-phonon phase spaces. The κL of AgI calculated using MD phonon lifetimes including full-order lattice anharmonicity shows a better agreement with experiments. acknowledgement: This work is supported by the Research Grants Council of Hong Kong (Grants No. 17318122 and No. 17306721). The authors are grateful for the research computing facilities offered by ITS, HKU. Z.Z. acknowledges the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 101034413. article_number: '174302' article_processing_charge: No article_type: original author: - first_name: Niuchang full_name: Ouyang, Niuchang last_name: Ouyang - first_name: Zezhu full_name: Zeng, Zezhu id: 54a2c730-803f-11ed-ab7e-95b29d2680e7 last_name: Zeng - first_name: Chen full_name: Wang, Chen last_name: Wang - first_name: Qi full_name: Wang, Qi last_name: Wang - first_name: Yue full_name: Chen, Yue last_name: Chen citation: ama: Ouyang N, Zeng Z, Wang C, Wang Q, Chen Y. Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I). Physical Review B. 2023;108(17). doi:10.1103/PhysRevB.108.174302 apa: Ouyang, N., Zeng, Z., Wang, C., Wang, Q., & Chen, Y. (2023). Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I). Physical Review B. American Physical Society. https://doi.org/10.1103/PhysRevB.108.174302 chicago: Ouyang, Niuchang, Zezhu Zeng, Chen Wang, Qi Wang, and Yue Chen. “Role of High-Order Lattice Anharmonicity in the Phonon Thermal Transport of Silver Halide AgX (X=Cl,Br, I).” Physical Review B. American Physical Society, 2023. https://doi.org/10.1103/PhysRevB.108.174302. ieee: N. Ouyang, Z. Zeng, C. Wang, Q. Wang, and Y. Chen, “Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I),” Physical Review B, vol. 108, no. 17. American Physical Society, 2023. ista: Ouyang N, Zeng Z, Wang C, Wang Q, Chen Y. 2023. Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I). Physical Review B. 108(17), 174302. mla: Ouyang, Niuchang, et al. “Role of High-Order Lattice Anharmonicity in the Phonon Thermal Transport of Silver Halide AgX (X=Cl,Br, I).” Physical Review B, vol. 108, no. 17, 174302, American Physical Society, 2023, doi:10.1103/PhysRevB.108.174302. short: N. Ouyang, Z. Zeng, C. Wang, Q. Wang, Y. Chen, Physical Review B 108 (2023). date_created: 2023-11-26T23:00:54Z date_published: 2023-11-01T00:00:00Z date_updated: 2023-11-28T07:48:55Z day: '01' department: - _id: BiCh doi: 10.1103/PhysRevB.108.174302 ec_funded: 1 intvolume: ' 108' issue: '17' language: - iso: eng month: '11' oa_version: None project: - _id: fc2ed2f7-9c52-11eb-aca3-c01059dda49c call_identifier: H2020 grant_number: '101034413' name: 'IST-BRIDGE: International postdoctoral program' publication: Physical Review B publication_identifier: eissn: - 2469-9969 issn: - 2469-9950 publication_status: published publisher: American Physical Society quality_controlled: '1' scopus_import: '1' status: public title: Role of high-order lattice anharmonicity in the phonon thermal transport of silver halide AgX (X=Cl,Br, I) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 108 year: '2023' ...