High-pressure phases of lithia Li2O:: First-principles calculations

The high- pressure ( HP ) structural properties of Li2O are examined theoretically using first- principles calculations ( density- functional theory ). The calculated results for the HP anticotunnite modification are compared to recent experimental studies. Our main focus is on the hexagonal Ni-2 In-type modification, which is a likely candidate for a HP phase of Li2O at pressures above 100 GPa. The structural aspects of a pressure- induced phase transition from anticotunnite to Ni2In are characterized in detail; the existence of precursor phenomena is pointed out.