14227 IUPAC Gold Book - symmetry breaking 10.1351/goldbook.14227 14227 current 1 Vanishing, in a specific crystal polymorph, of selected symmetry elements present in other crystal polymorphs, or in selected minimum energy conformations of isolated molecules of a given substance. The symmetry elements that vanish are frequently intramolecular. Symmetry breaking in polymers in such cases leads to deviations from the ideal crystalline chain conformation and from the equivalence postulate. Crystal polymorphs affected by symmetry breaking are usually stable at low temperature under conditions that optimize packing energy. crystal polymorph https://goldbook.iupac.org//terms/view/14219 ideal crystalline chain conformation https://goldbook.iupac.org//terms/view/14210 PAC, 2011, 83, 1831. 'Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)' on page 1847 (https://doi.org/10.1351/PAC-REC-10-11-13) https://goldbook.iupac.org/terms/view/14227/html https://goldbook.iupac.org/terms/view/14227/json https://goldbook.iupac.org/terms/view/14227/plain Citation: 'symmetry breaking' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.14227 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-06-29T00:19:37+00:00