Orbital-free density functional theory applied to NaAlH4

We present the application of orbital-free density functional theory (OF-I)FT) to NaAlH4, a potential hydrogen storage material, and related systems. Although the simple Al and NaH structures are reproduced reasonably well by OF-DFT, the approach fails for the more complex NaAlH4 structure. Calculations on AlH3 show that the failure to describe the Al-H interaction is related to the kinetic energy functionals used rather than the local pseudopotentials which are required within the OF-DFT approach, Thus. systems such as NaAlH4 present a challenge which awaits the development of more reliable orbital-free kinetic energy functionals.