Intermediate cerium valence intermetallics Ce4RuMg, Ce23Ru7Mg4, CeRu2Mg5, and Ce2Ru4Mg17: Electronic structures and chemical bonding from DFT

The electronic structures of the intermediate-valent cerium compounds Ce4RuMg, Ce23Ru7Mg4, CeRu2Mg5, and Ce2Ru4Mg17 were studied ab-initio by DFT calculations. Common structural characteristics are short Ce∼4+–Ru bonds accompanied by intermediate-valent or almost tetravalent cerium. The degree of depletion of the cerium 4f shell is well monitored in the DOS plots, paralleled by strong covalent Ce–Ru bonding. We also derive magnitudes for the electronic contribution to the specific heat of these compounds in order to appreciate their intermediate valence behaviours.