@article {Welchman2014,
	title = {Positional disorder in ammonia borane at ambient conditions},
	journal = {Physical Review B},
	volume = {89},
	number = {18},
	year = {2014},
	month = {may},
	pages = {180101},
	publisher = {Amer Physical Soc},
	abstract = {We solve a long-standing experimental discrepancy of NH3BH3, which-as a molecule-has a threefold rotational axis, but in its crystallized form at room temperature shows a fourfold symmetry around the same axis, creating a geometric incompatibility. To explain this peculiar experimental result, we study the dynamics of this system with ab initio Car-Parrinello molecular dynamics and nudged-elastic band simulations. We find that rotations, rather than spatial static disorder, at angular velocities of 2 rev/ps-a time scale too small to be resolved by standard experimental techniques-are responsible for the fourfold symmetry.},
	keywords = {AMIDOBORANES, BH3NH3, DYNAMICS, HIGH-PRESSURE, NEUTRON, PHASE, POTENTIAL HYDROGEN STORAGE, TORSIONAL BARRIER},
	doi = {10.1103/PhysRevB.89.180101},
	author = {Welchman, E. and Giannozzi, P. and Thonhauser, T.}
}
