Local atomic order and infrared spectra of biogenic calcite

Shining light on local order: The relations between local crystalline order and peak intensities in the infrared spectra of calcite are explained in terms of different sensitivities to Ca-O and O⋯O distances (see picture) by comparing ab initio phonon spectra for ideal and distorted calcite unit cells with experimental spectra of various biogenic and geological calcites. (Figure Presented).