Orbital-free density functional theory applied to NaAlH4

Area of Science:

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

Background:

• Sodium aluminum hydride (NaAlH4) is a promising material for hydrogen storage.
• Orbital-free density functional theory (OF-DFT) offers a computationally efficient alternative to traditional DFT methods.

Purpose of the Study:

• To evaluate the applicability of OF-DFT for modeling NaAlH4 and related systems.
• To identify the limitations of OF-DFT in describing the electronic structure and interactions within these materials.

Main Methods:

• Application of OF-DFT to simple Al and NaH structures.
• Application of OF-DFT to the complex NaAlH4 structure.
• Investigating the Al-H interaction using OF-DFT calculations on AlH3.

Main Results:

• OF-DFT accurately reproduced simple Al and NaH structures.
• OF-DFT failed to accurately describe the complex NaAlH4 structure.
• The failure in NaAlH4 was attributed to limitations in kinetic energy functionals, not pseudopotentials.

Conclusions:

• Current OF-DFT methods are inadequate for accurately modeling complex hydrogen storage materials like NaAlH4.
• Further development of reliable kinetic energy functionals is crucial for advancing OF-DFT applications in materials science.