Structure of ice VII with Hirshfeld atom refinement

In the refinement of the crystal structures of ice, the best results obtained so far have been with neutron diffraction because the most troublemaking aspects are the hydrogen atoms. In nine out of twenty ice structures, the hydrogen atoms are disordered, which makes proper refinement more difficult...

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Main Authors: Roman Gajda, Michał Chodkiewicz, Dongzhou Zhang, Phuong Nguyen, Vitali Prakapenka, Krzysztof Wozniak
Format: Article
Language:English
Published: International Union of Crystallography 2025-05-01
Series:IUCrJ
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Online Access:https://journals.iucr.org/paper?S2052252525002581
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author Roman Gajda
Michał Chodkiewicz
Dongzhou Zhang
Phuong Nguyen
Vitali Prakapenka
Krzysztof Wozniak
author_facet Roman Gajda
Michał Chodkiewicz
Dongzhou Zhang
Phuong Nguyen
Vitali Prakapenka
Krzysztof Wozniak
author_sort Roman Gajda
collection DOAJ
description In the refinement of the crystal structures of ice, the best results obtained so far have been with neutron diffraction because the most troublemaking aspects are the hydrogen atoms. In nine out of twenty ice structures, the hydrogen atoms are disordered, which makes proper refinement more difficult. In our previous paper describing the structure of ice VI we proved that, using Hirshfeld atom refinement (HAR) based on synchrotron X-ray data, it is possible to obtain results comparable with those from neutron experiments. In this work, we investigate another structure of high-pressure disordered ice, cubo-ice (ice VII). Single crystals of cubo-ice were grown under pressure in diamond anvil cells. X-ray diffraction measurements were conducted at a synchrotron source facility (APS, University of Chicago, USA) as well as on our regular in-house laboratory diffractometer with Ag radiation. The data collected were further refined with HAR. Comparison of the structural parameters obtained with those derived from neutron diffraction showed very good agreement in terms of bond lengths and fairly good agreement in terms of hydrogen atom ADPs. We were also able to perform unconstrained refinements with various split-atom models.
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institution Kabale University
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publisher International Union of Crystallography
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spelling doaj-art-69cf6862759847f8b90892cf28155c692025-08-20T03:48:31ZengInternational Union of CrystallographyIUCrJ2052-25252025-05-0112328829410.1107/S2052252525002581lt5074Structure of ice VII with Hirshfeld atom refinementRoman Gajda0Michał Chodkiewicz1Dongzhou Zhang2Phuong Nguyen3Vitali Prakapenka4Krzysztof Wozniak5Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Żwirki i Wigury 101, Warszawa 02-089, PolandBiological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Żwirki i Wigury 101, Warszawa 02-089, PolandGeoSoilEnviroCARS, University of Chicago, 9700 S. Cass Avenue, Argonne, IL 60439, USAGeoSoilEnviroCARS, University of Chicago, 9700 S. Cass Avenue, Argonne, IL 60439, USAGeoSoilEnviroCARS, University of Chicago, 9700 S. Cass Avenue, Argonne, IL 60439, USABiological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Żwirki i Wigury 101, Warszawa 02-089, PolandIn the refinement of the crystal structures of ice, the best results obtained so far have been with neutron diffraction because the most troublemaking aspects are the hydrogen atoms. In nine out of twenty ice structures, the hydrogen atoms are disordered, which makes proper refinement more difficult. In our previous paper describing the structure of ice VI we proved that, using Hirshfeld atom refinement (HAR) based on synchrotron X-ray data, it is possible to obtain results comparable with those from neutron experiments. In this work, we investigate another structure of high-pressure disordered ice, cubo-ice (ice VII). Single crystals of cubo-ice were grown under pressure in diamond anvil cells. X-ray diffraction measurements were conducted at a synchrotron source facility (APS, University of Chicago, USA) as well as on our regular in-house laboratory diffractometer with Ag radiation. The data collected were further refined with HAR. Comparison of the structural parameters obtained with those derived from neutron diffraction showed very good agreement in terms of bond lengths and fairly good agreement in terms of hydrogen atom ADPs. We were also able to perform unconstrained refinements with various split-atom models.https://journals.iucr.org/paper?S2052252525002581hirshfeld atom refinementcubo-iceice vii structureanisotropic displacement parameters
spellingShingle Roman Gajda
Michał Chodkiewicz
Dongzhou Zhang
Phuong Nguyen
Vitali Prakapenka
Krzysztof Wozniak
Structure of ice VII with Hirshfeld atom refinement
IUCrJ
hirshfeld atom refinement
cubo-ice
ice vii structure
anisotropic displacement parameters
title Structure of ice VII with Hirshfeld atom refinement
title_full Structure of ice VII with Hirshfeld atom refinement
title_fullStr Structure of ice VII with Hirshfeld atom refinement
title_full_unstemmed Structure of ice VII with Hirshfeld atom refinement
title_short Structure of ice VII with Hirshfeld atom refinement
title_sort structure of ice vii with hirshfeld atom refinement
topic hirshfeld atom refinement
cubo-ice
ice vii structure
anisotropic displacement parameters
url https://journals.iucr.org/paper?S2052252525002581
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AT michałchodkiewicz structureoficeviiwithhirshfeldatomrefinement
AT dongzhouzhang structureoficeviiwithhirshfeldatomrefinement
AT phuongnguyen structureoficeviiwithhirshfeldatomrefinement
AT vitaliprakapenka structureoficeviiwithhirshfeldatomrefinement
AT krzysztofwozniak structureoficeviiwithhirshfeldatomrefinement