Recently, a number of ground-state structures of LiBH 4 have been proposed, both from experimental and computational works. The results show controversy between computational and experimental ground-state crystal structures of LiBH 4. In order to determine which is truly the lowest in energy, we study LiBH 4 in a variety of crystal structures using density functional theory (DFT) calculations of the free energy (T=0 K total energy plus vibrational thermodynamics), employing a variety of DFT methods and exchange-correlation functionals. Our calculations show that the experimentally observed structures are lowest in energy in DFT. However, multiple LiBH 4 structures are degenerate with the experimental ground-state crystal structure and there exists a relatively flat potential energy landscape between them. These degenerate structures include the recently theoretically predicted LiBH 4 structure, which the authors claimed to be 9.66 kJ/(mol LiBH 4) (or ∼100 meV/fu) lower in energy than the experimentally XRD determined LiBH 4 structure. Our calculations do not support these previous claims, and hence resolve this discrepancy between DFT and experiment.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Sep 19 2012|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics