Formation of As–As Interlayer Bonding in the cT Phase of EuFe2As2 and CeFeAsO Under Pressure from First Principle
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The electronic band structure and structural phase stability of EuFe2As2 and CeFeAsO compounds were studied using the full-potential linearized augmented plane wave (FP-LAPW) method implemented using WIEN2k. To calculate the structural stability and phase transition of these compounds, the total energies have been computed as a function of reduced volumes and fitted with the Birch–Murnaghan equation. The calculated lattice parameters are found to be in agreement with the available experimental data. The present results show that EuFe2As2 and CeFeAsO compounds undergo structural phase transition from body-centered tetragonal (BCT) into collapsed tetragonal (cT) and tetragonal (T) into cT phase under pressure. The calculated phase transition pressures are in agreement with recent experimental data. The calculated valence charge density of collapsed tetragonal phase reveals that As–As interactions found to be stronger under pressure.
KeywordsRare-earth transition metal pnictides Electronic structure Ab initio method Structural phase stability Phase transition
The authors are thankful to Professors Peter Blaha, Karlheinz Schwarz, Georg Madsen, Dieter Kvasnicka, and Joachim Luitz, Institute of Physical and Theoretical Chemistry, Vienna University of Technology, Getreidemarkt 9/156, A-1060, Vienna, Austria, for providing the WIEN2k code.
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