Exploiting Exchange-Correlation Functionals' Performance for Structure and Property Prediction of the NaAlP₂O₇ Solid...

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Density functional theory (DFT) is crucial for materials research, with exchange-correlation functional choice impacting accuracy.
• Developing novel solid electrolytes (SEs) for sodium-ion batteries (NIBs) is essential for improving energy storage technologies.
• NaAlP2O7 is investigated as a potential SE, but its properties require precise computational evaluation.

Purpose of the Study:

• To compare the performance of different DFT exchange-correlation functionals (PBE, PBEsol, SCAN, r2SCAN) for NaAlP2O7.
• To evaluate the energetics, mechanical, electronic, and structural properties of NaAlP2O7 as a potential solid electrolyte.
• To determine the most reliable functional for accurate predictions of NaAlP2O7 properties.

Main Methods:

• First-principles calculations using DFT.
• Comparison of Perdew-Burke-Ernzerhof (PBE) and Strongly Constrained and Appropriately Normed (SCAN) meta-GGA approximations.
• Analysis of structural, mechanical, electronic, and thermodynamic stability, including vibrational analysis.

Main Results:

• PBEsol accurately predicted lattice parameters, aligning with experimental data.
• r2SCAN demonstrated superior accuracy in predicting structural and electronic properties of NaAlP2O7 compared to PBE and PBEsol.
• NaAlP2O7 is structurally, mechanically, electronically, and thermodynamically stable, but exhibits vibrational instability indicated by imaginary frequencies.

Conclusions:

• The selection of appropriate DFT functionals is critical for accurate solid electrolyte computations.
• r2SCAN is identified as a promising functional for calculating the properties of NaAlP2O7.
• Vibrational instability in NaAlP2O7 may hinder its performance as a solid electrolyte in sodium-ion batteries due to ion scattering.