Balancing accuracy and efficiency in density functional theory studies of SiO₂ polymorphs.

Area of Science:

• Computational materials science
• Solid-state chemistry
• Quantum chemistry

Background:

• Density functional theory (DFT) is crucial for predicting material properties.
• Previous studies on silica polymorphs using DFT were limited in scope.
• Accurate prediction of framework densities and relative stabilities is essential for materials design.

Purpose of the Study:

• To comprehensively assess dispersion-corrected DFT methods for silica polymorphs.
• To compare 27 semilocal DFT approaches, including Grimme-type D3 corrections and nonlocal functionals.
• To validate calculations against experimental data for framework densities and relative energies.

Main Methods:

• Utilized the Gaussian and plane wave DFT code CP2K.
• Evaluated 27 semilocal DFT approaches with dispersion corrections.
• Assessed the impact of basis set size on calculation accuracy.
• Performed structure optimizations for complex zeolite structures.

Main Results:

• Identified DFT functionals achieving low errors (0.2 T atoms/1000 ų for density, 1.0 kJ/mol for energy).
• Demonstrated that larger basis sets offer marginal improvements, especially for relative energies.
• Confirmed the feasibility of routine structure optimizations for complex zeolites using CP2K.

Conclusions:

• Dispersion-corrected DFT, particularly with specific functionals, can accurately reproduce silica polymorph properties.
• CP2K offers efficient computation for complex zeolite structures.
• The study provides a robust benchmark for selecting DFT methods in silica research.