Anharmonicity of inner-OH stretching modes in hydrous phyllosilicates: assessment from first-principles frozen-phonon calculations | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Anharmonicity of inner-OH stretching modes in hydrous phyllosilicates: assessment from first-principles frozen-phonon calculations

Type de publication:

Journal Article

Source:

Physics and Chemistry of Minerals, Volume 34, Ticket 9, p.621-625 (2007)

ISBN:

0342-1791

Numéro d'accès:

ISI:000250486200003

Mots-clés:

UMR 7154 ; Minéralogie ; N° Contribution : 2257

Résumé:

The theoretical anharmonicity of the inner-OH stretching modes of kaolinite and lizardite is determined using a frozen-phonon approach. The anharmonicity parameter, defined as the difference between half the first overtone frequency and the frequency of the fundamental transition, is -95 and -92 cm(-1) for kaolinite and lizardite, respectively. These values are consistent with the experimental measurements. The very good agreement usually observed between harmonic calculations of vibrational frequencies at the density functional theory (DFT) level, using the generalized gradient approximation (GGA), and experimental positions of vibrational bands results from the fortuitous, but almost exact, cancelation of two types of errors. One is related to the GGA approximation and the other to the neglect of anharmonicity.

Notes:

Balan, Etienne Lazzeri, Michele Delattre, Simon Meheut, Merlin Refson, Keith Winkler, Bjoern