Ab initio vibrational spectra and dielectric properties of carbonates: magnesite, calcite and dolomite |
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Authors: | L Valenzano Y Noël R Orlando C M Zicovich-Wilson M Ferrero R Dovesi |
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Institution: | (1) Dipartimento di Chimica IFM, Università di Torino and NIS (Nanostructured Interfaces and Surfaces), Via P. Giuria 5, 10125 Torino, Italy;(2) Laboratoire de Pétrologie, Modélisation de Matériaux et Processus, UMR 7160, Université Pierre et Marie Curie, 4 Place Jussieu, 75232 Paris cedex 05, France;(3) Dipartimento di Scienze e Tecnologie Avanzate, Università del Piemonte Orientale, Via Bellini 25/G, 15100 Alessandria, Italy;(4) Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col Chamilpa, 62210 Cuernavaca (MOR), Mexico;(5) Dipartimento di Chimica IFM, Università di Torino and NIS (Nanostructured Interfaces and Surfaces), Via P. Giuria 7, 10125 Torino, Italy;(6) Dipartimento di Chimica IFM, Università di Torino and NIS (Nanostructured Interfaces and Surfaces), Centre of Excellence, Via P. Giuria 7, 10125 Torino, Italy |
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Abstract: | The equilibrium geometry, the Raman and IR vibrational spectra at the Γ point, TO–LO splitting, IR intensities, Born and dielectric
tensors of magnesite MgCO3, dolomite MgCa(CO3)2 and calcite CaCO3 have been calculated with the periodic ab initio program CRYSTAL, by using an all-electron gaussian type basis set and the
B3LYP hamiltonian. LO (longitudinal-optical) modes are computed by correcting the dynamical matrix through Born charges and
high frequency dielectric tensors obtained from well localized Wannier functions and a saw-tooth computational scheme. The
mean absolute difference between calculated and experimental frequencies (IR TO and LO and RAMAN) is as small as 6.9 cm−1 for magnesite, 7.7 cm−1 for dolomite and 8.5 cm−1 for calcite. Calculated IR intensities are in semiquantitative agreement with experiment. The modes of the three compounds
are compared through graphical animation available on the CRYSTAL web-site. |
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Keywords: | Vibrations Carbonates IR intensities Dielectric tensor Ab initio simulation |
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