Коливні спектри кристала (NH4)2BeF4 у параелектричній фазі
The vibrational spectra of the (NH4)2BeF4 crystal in the paraelectric phase (the space group symmetry No. 62) have been studied. In the framework of the group-theoretical analysis, the symmetry of vibrations in the crystal is classified. Using the first-principles approach and in the framework of th...
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| Date: | 2025 |
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| Main Authors: | , , , |
| Format: | Article |
| Language: | English Ukrainian |
| Published: |
Publishing house "Academperiodika"
2025
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| Subjects: | |
| Online Access: | https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2023531 |
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| Journal Title: | Ukrainian Journal of Physics |
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Ukrainian Journal of Physics| Summary: | The vibrational spectra of the (NH4)2BeF4 crystal in the paraelectric phase (the space group symmetry No. 62) have been studied. In the framework of the group-theoretical analysis, the symmetry of vibrations in the crystal is classified. Using the first-principles approach and in the framework of the density functional theory and the density perturbation functional theory, the dispersion of phonons and the frequencies of the vibrational spectrum of the (NH4)2BeF4 crystal are calculated. To describe the exchange-correlation interaction of electrons, the generalized gradient approximation is applied. 180 vibrational modes are found in the vibrational spectrum of the examined crystal. The infrared and Raman spectra of the (NH4)2BeF4 crystal are calculated and compared with experimental ones. |
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