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Abstract <p>Structural parameters of Mg<sub>2</sub>N<i>A</i> (<i>A</i>&#xa0;=&#xa0;F, Cl, Br, I) crystals with antichalcopyrite and anti-LiFeO<sub>2</sub> structures are determined and their vibrational spectra are studied using the density functional theory (DFT). It is shown that that the chloride, bromide, and iodide spectra contain features in the form of acoustic branches with imaginary frequencies characteristic for unstable structures. For Mg<sub>2</sub>NF, the energetically optimal path of the structural transition to the stable state is calculated. The transition path contains additional intermediate minima, for which symmetry and parameters of the corresponding crystal structures are determined. On this basis, a mechanism of a structural phase transition to Mg<sub>2</sub>NF is proposed.</p>

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DFT Study of Lattice Dynamics and Phase Transitions of Mg2NA (A = F, Cl, Br, I) Compounds in Antichalcopyrite and Anti-LiFeO2 Structures

  • 期刊论文

  • 发表日期：

    2025年8月29日

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  • V. S. Timofeev,
  • A. B. Gordienko

摘要

Abstract

Structural parameters of Mg2NA (A = F, Cl, Br, I) crystals with antichalcopyrite and anti-LiFeO2 structures are determined and their vibrational spectra are studied using the density functional theory (DFT). It is shown that that the chloride, bromide, and iodide spectra contain features in the form of acoustic branches with imaginary frequencies characteristic for unstable structures. For Mg2NF, the energetically optimal path of the structural transition to the stable state is calculated. The transition path contains additional intermediate minima, for which symmetry and parameters of the corresponding crystal structures are determined. On this basis, a mechanism of a structural phase transition to Mg2NF is proposed.