Physics

Bond length

Chemical bond

Organic chemistry

Computational chemistry

Chemical physics

Nuclear physics

Chemistry

Molecule

Quantum mechanics

Quantum chemical

Uranium

Quantum

Nature Chemistry

Understanding the bonding, reactivity and electronic structure of actinides is lagging behind that of the rest of the periodic table. This can be partly explained by the challenges that one faces in experimental studies of such radioactive compounds and also by the need to properly account for relativistic effects in theoretical studies. A further challenge is the very complicated electronic structures encountered in actinide chemistry, as vividly illustrated by the naked diuranium molecule U2. Here we report a computational study of this emblematic molecule using state-of-the-art relativistic quantum chemical methods. Notably, the variational inclusion of spin–orbit interactions leads not only to a different electronic ground state, but also to a lower bond multiplicity compared with those in previous studies. Establishing a fundamental understanding of the electronic structure of actinides remains a challenging task for both experiment and theory. Now, it is shown that for the uranium dimer, relativity and electron correlation affects not only the nature of the electronic ground state, but also lowers the bond multiplicity in comparison to previous studies.

Relativistic quantum chemical calculations show that the uranium molecule U2 has a quadruple bond