Lattice anisotropy, electronic and chemical structures of uranyl carbonate, UO2CO3, from first principles

Band theoretical results are presented on UO2CO3, based on computations within the density functional theory. The equation of state is obtained with equilibrium lattice properties in agreement with experiment. For isotropic volume change the bulk modulus amounts to 176 GPa. A higher value for anisotropic compression along the linear uranyl characterizes its incompressibility. The electronic band structure shows a semiconducting behavior (∼2 eV band gap) with little band dispersion. From chemical bonding plots and electron localization function mapping, oxygen atoms are found to preferentially bind with uranium for one sublattice and to carbon forming the carbonate ions for the two others. This further illustrates the ionic-like (UO2)2+(CO3)2− chemical picture.