Ab initio quantum mechanical modeling of infrared vibrational frequencies of the OH group in dioctahedral phyllosilicates. Part I: Methods, results and comparison to experimental data

摘要

The infrared (IR) spectra of small clusters of atoms ([MM'(OH)₂] and [MM' (OH)₂ (H₂O)₆], where M, M' = Al3+, Mg2+, Fe2+, Fe3+) mimicking the environment of the OH group in dioctahedral phyllosilicates have been modeled using ab initio quantum mechanical calculations. These modeling results are relevant to establishing the connections between IR spectra of phyllosilicates and their composition, and to investigate the utility of quantum mechanical models for calculating IR frequencies of minerals. This study focused on the OH stretch and in-plane bend fundamentals, because they give rise to a combination band near 4545 cm–1 (2.2 µm) that can be observed in imaging spectrometer or hyperspectral remote sensing data.