Oxide crystals with specific infrared spectra are widely used in the optical energy industry. Conventional density functional theory calculations reveal various properties of oxide crystals, including their electronic band structure, electronic density of states, vibrational modes, phonon band structure, and phonon density of states, but only provide qualitative analyses of infrared spectra. Herein, we provide a theoretical approach to analyzing how the basic mechanisms of infrared absorption are affected by the above properties and then predicting quantitatively the infrared spectra. The derivation and details of this method are clarified, and the CeO2 and LaAlO3 infrared spectra are finally calculated through an application. The calculated infrared properties are in good agreement with previously reported experiments, demonstrating the accuracy of our method. This study provides a less expensive approach to identifying the infrared spectra of oxide crystals through the use of theoretical calculations and is potentially applicable in the optical energy industry, improving the efficiency by which appropriate materials can be selected.
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