  Under pressure many rare earths and actinide metals transform to a-U
structure or its lower symmetry distorted forms. We have reinterpreted the
diffraction data of Dabos et al for Pu (reference 4) and find that a Am IV type
distorted a-U structure in Pnma space group can explain this for its high
pressure phase. The structures of this phase and a-Pu are both shown to have a
distorted hcp topology. The upturn in the atomic volume of Pu at 0.1 MPa can
also be rationalized on the basis of this proposal
