First principles study of the electronic and magnetic structures and bonding properties of UCoC2 ternary, characteristic of C–C units

The electronic structure of UCoC2, a di-carbide with the C–C units is examined from ab initio with an assessment of the properties of chemical bonding. The energy–volume equation of state shows large anisotropy effects due to C–C alignment along tetragonal c-axis leading to high linear incompressibility. Relevant features of selective bonding of uranium and cobalt with carbon at two different Wyckoff sites and strong C–C interactions are remarkable. The vibrational frequencies for C⋯C stretching modes indicate closer behavior to aliphatic C–C rather than CC double bond. A ferromagnetic ground state is proposed from the calculations.

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► C2 units in UCoC2 lead to site selective bonding with U/Co and C1 → C2 bond dipole moment.
► Elastic constants and E(V) EOS show large anisotropy effects due to C⋯C along c-axis.
► Vibration frequencies for C⋯C stretching ∼1000 cm−1 closer to C–C versus CC.
► Ferromagnetic ground state from energy differences with band magnetism characteristics.