Experimental and Theoretical Confirmation of Covalent Bonding in α‐Pu

Abstract Plutonium's radioactivity provides functionality for nuclear batteries, nuclear reactors, etc., but its complex electronic properties harbor strongly correlated behavior giving rise to a host of interesting phenomena including the presence of a ca. 25% volume collapse between δ‐Pu and α‐Pu. The complex bonding environments of the ground state allotrope, α‐Pu, serve as a unique testing ground for new computational and experimental approaches within the Pu science community. For the first time, a combination of novel ansatzes is used in all‐electron density functional theory (DFT) and pair distribution functions (PDF) obtained from high‐Q X‐ray diffraction to study the bonding behavior in α‐Pu. This first experimental and theoretical co‐informed description of local bonding behavior for α‐Pu reveals covalent bonds, which is a topic that remains of interest in this allotrope. The covalent bonding present at the atomistic level accounts for several of α‐Pu's macropscopic properties (e.g., Poisson's ratio) that in turn explains its physical functionalities relative to other allotropic phases like δ‐Pu.