title: First principles simulation of a superionic phase of hydrogen fluoride (HF) at high pressures and temperatures.
abstract: We have conducted ab initio molecular dynamics simulations of hydrogen fluoride (HF) at pressures of 5-66 GPa along the 900 K isotherm. We predict a superionic phase at 33 GPa, where the fluorine atoms are fixed in a bcc lattice while the hydrogen atoms diffuse rapidly with a diffusion constant between 2 x 10(-5) and 5 x 10(-5)cm(2)s. We find that a transformation from asymmetric to symmetric hydrogen bonding occurs in HF at 66 GPa and 900 K. With superionic HF we have discovered a model system where symmetric hydrogen bonding occurs at experimentally achievable conditions. Given previous results on superionic H(2)O [Goldman et al., Phys. Rev. Lett. 94, 217801 (2005)] and NH(3) [Cavazzoni et al., Science 283, 44 (1999)], we conclude that high P, T superionic phases of electronegative element hydrides could be common.
authors.affiliation: Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA. goldman14@llnl.gov
authors.forename: Nir
authors.initials: N
authors.lastname: Goldman
authors.forename: Laurence E
authors.initials: LE
authors.lastname: Fried