{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,17]],"date-time":"2026-05-17T07:01:20Z","timestamp":1779001280647,"version":"3.51.4"},"reference-count":48,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,9,7]],"date-time":"2021-09-07T00:00:00Z","timestamp":1630972800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>The phase transitions between paraelectric (PE) and ferroelectric (FE) isomorph phases of LiNbO3 have been investigated quantum mechanically by using a Gaussian-type basis set, the B3LYP hybrid functional and the CRYSTAL17 code. The structural, electronic and vibrational properties of the two phases are analyzed. The vibrational frequencies evaluated at the \u0393 point indicate that the paraelectric phase is unstable, with a complex saddle point with four negative eigenvalues. The energy scan of the A2u mode at \u2212215 cm\u22121 (i215) shows a dumbbell potential with two symmetric minima. The isotopic substitution, performed on the Li and Nb atoms, allows interpretation of the nontrivial mechanism of the phase transition. The ferroelectric phase is more stable than the paraelectric one by 0.32 eV.<\/jats:p>","DOI":"10.3390\/sym13091650","type":"journal-article","created":{"date-parts":[[2021,9,8]],"date-time":"2021-09-08T02:41:07Z","timestamp":1631068867000},"page":"1650","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Vibrational Analysis of Paraelectric\u2013Ferroelectric Transition of LiNbO3: An Ab-Initio Quantum Mechanical Treatment"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2853-5643","authenticated-orcid":false,"given":"Francesco Silvio","family":"Gentile","sequence":"first","affiliation":[{"name":"Department of Chemical Sciences, Universit\u00e0 degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant\u2019Angelo, Via Cintia, 21-80126 Napoli, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rosita","family":"Diana","sequence":"additional","affiliation":[{"name":"Department of Agriculture, University of Napoli Federico II, 80055 Naples, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9253-0794","authenticated-orcid":false,"given":"Barbara","family":"Panunzi","sequence":"additional","affiliation":[{"name":"Department of Agriculture, University of Napoli Federico II, 80055 Naples, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0572-5436","authenticated-orcid":false,"given":"Ugo","family":"Caruso","sequence":"additional","affiliation":[{"name":"Department of Chemical Sciences, Universit\u00e0 degli Studi di Napoli Federico II, Complesso Universitario di Monte Sant\u2019Angelo, Via Cintia, 21-80126 Napoli, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8800-3411","authenticated-orcid":false,"given":"Alexander","family":"Platonenko","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV1063 Riga, Latvia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fabien","family":"Pascale","sequence":"additional","affiliation":[{"name":"Laboratoire de Physique et Chimie Th\u00e9oriques, Universit\u00e9 de Lorraine\u2014Nancy, CNRS, 54506 Nancy, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Roberto","family":"Dovesi","sequence":"additional","affiliation":[{"name":"Departiment of Chimistry, Universit\u00e0 di Torino and NIS (Nanostructured Interfaces and Surfaces) Centre, via P. Giuria 5, 10125 Torino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9405","DOI":"10.1021\/ja2010362","article-title":"Perovskite, LiNbO3, Corundum, and Hexagonal Polymorphs of (In1\u2013x M x) MO3","volume":"133","author":"Belik","year":"2011","journal-title":"J. Am. Chem. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"064113","DOI":"10.1103\/PhysRevB.73.064113","article-title":"Dopant Occupancy and Structural Stability of Doped Lithium Niobate Crystals","volume":"73","author":"Xue","year":"2006","journal-title":"Phys. Rev. B"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1016\/j.optmat.2005.04.007","article-title":"Optical Properties of MgO Doped LiNbO3 Single Crystals","volume":"28","author":"Choubey","year":"2006","journal-title":"Opt. 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