Novel R3¯m phase of beryllium under high pressure

We find a novel R3¯m phase under high pressure by using first-principles calculations in combination with calypso algorithm. We studied the evolution of kinetic barrier employing the climbing image nudged elastic band method and observed a relatively low kinetic barrier between the hcp phase and R3¯m phase. Further calculations showed that the kinetic barrier decreases with increasing pressure. The two phases are identified to dynamically coexist in a pressure range of 300-380 GPa. In addition, the phonon anomaly suggests the structural rearrangement associated with the phase coexistence.