Andrei Postnikov, Anna Majtyka-Piłat, Dariusz Chrobak, Józef Deniszczyk
{"title":"二水六羟基二锌酸钙(qatranaite)的计算振动光谱。","authors":"Andrei Postnikov, Anna Majtyka-Piłat, Dariusz Chrobak, Józef Deniszczyk","doi":"10.1016/j.saa.2024.124414","DOIUrl":null,"url":null,"abstract":"<p><p>On the basis of first-principles electronic structure calculations, crystallographic parameters have been refined for calcium hydroxozincate (Qatranaite mineral), and the vibration properties (frequencies and eigenvectors) calculated. A detailed analysis of vibration modes is done, in the context of comparison with infrared and Raman spectra previously available. Special attention is paid to a posteriori symmetry analysis of vibration modes, discussing the latters' attribution to four irreducible representations of the P2<sub>1</sub>/c space group, and to identifying stretchings and bendings of particular chemical bonds, pronounced in different vibrations. It turns out that high-frequency (>700 cm<sup>-1</sup>) vibrations of hydroxyl groups bridging the Ca or Zn cations differ quite considerably for crystallographically distinct hydroxyl positions. It is shown that the vibrations involving hydroxyl groups and crystalline water typically come about in quadruplets at very close frequencies, whereby different irreducible representations reflect different combinations of similar \"molecular\" vibrations of four identical entities (of each hydroxyl or water) present in the unit cell. However, some vibrations show exceptions from this rule. In addition to interpretation of earlier experimental investigations, our study indicates that the low-frequency (<700 cm<sup>-1</sup>) vibrations within the cation-hydroxyl connected skeleton are of more \"solid-state-like\" character and cannot be reasonably interpreted in terms of \"molecular\" vibrations within ZnO<sub>4</sub> or CaO<sub>6</sub> units.</p>","PeriodicalId":94213,"journal":{"name":"Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy","volume":"318 ","pages":"124414"},"PeriodicalIF":0.0000,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Calculated vibration spectrum of calcium hexahydroxodizincate dihydrate (qatranaite).\",\"authors\":\"Andrei Postnikov, Anna Majtyka-Piłat, Dariusz Chrobak, Józef Deniszczyk\",\"doi\":\"10.1016/j.saa.2024.124414\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>On the basis of first-principles electronic structure calculations, crystallographic parameters have been refined for calcium hydroxozincate (Qatranaite mineral), and the vibration properties (frequencies and eigenvectors) calculated. A detailed analysis of vibration modes is done, in the context of comparison with infrared and Raman spectra previously available. Special attention is paid to a posteriori symmetry analysis of vibration modes, discussing the latters' attribution to four irreducible representations of the P2<sub>1</sub>/c space group, and to identifying stretchings and bendings of particular chemical bonds, pronounced in different vibrations. It turns out that high-frequency (>700 cm<sup>-1</sup>) vibrations of hydroxyl groups bridging the Ca or Zn cations differ quite considerably for crystallographically distinct hydroxyl positions. It is shown that the vibrations involving hydroxyl groups and crystalline water typically come about in quadruplets at very close frequencies, whereby different irreducible representations reflect different combinations of similar \\\"molecular\\\" vibrations of four identical entities (of each hydroxyl or water) present in the unit cell. However, some vibrations show exceptions from this rule. In addition to interpretation of earlier experimental investigations, our study indicates that the low-frequency (<700 cm<sup>-1</sup>) vibrations within the cation-hydroxyl connected skeleton are of more \\\"solid-state-like\\\" character and cannot be reasonably interpreted in terms of \\\"molecular\\\" vibrations within ZnO<sub>4</sub> or CaO<sub>6</sub> units.</p>\",\"PeriodicalId\":94213,\"journal\":{\"name\":\"Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy\",\"volume\":\"318 \",\"pages\":\"124414\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-10-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Spectrochimica acta. 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Calculated vibration spectrum of calcium hexahydroxodizincate dihydrate (qatranaite).
On the basis of first-principles electronic structure calculations, crystallographic parameters have been refined for calcium hydroxozincate (Qatranaite mineral), and the vibration properties (frequencies and eigenvectors) calculated. A detailed analysis of vibration modes is done, in the context of comparison with infrared and Raman spectra previously available. Special attention is paid to a posteriori symmetry analysis of vibration modes, discussing the latters' attribution to four irreducible representations of the P21/c space group, and to identifying stretchings and bendings of particular chemical bonds, pronounced in different vibrations. It turns out that high-frequency (>700 cm-1) vibrations of hydroxyl groups bridging the Ca or Zn cations differ quite considerably for crystallographically distinct hydroxyl positions. It is shown that the vibrations involving hydroxyl groups and crystalline water typically come about in quadruplets at very close frequencies, whereby different irreducible representations reflect different combinations of similar "molecular" vibrations of four identical entities (of each hydroxyl or water) present in the unit cell. However, some vibrations show exceptions from this rule. In addition to interpretation of earlier experimental investigations, our study indicates that the low-frequency (<700 cm-1) vibrations within the cation-hydroxyl connected skeleton are of more "solid-state-like" character and cannot be reasonably interpreted in terms of "molecular" vibrations within ZnO4 or CaO6 units.