Orbital-Selective Electronic Correlations and Quantum Criticality in a Hybridization Modulation Intermetallic Compound CeCoSi_<b>2</b>

We investigate the electronic structure and correlation effects in CeCoSi2 using a combined density functional theory and a dynamical mean-field theory approach. Our results reveal orbital-selective quasiparticle renormalization, with Ce 4f electrons exhibiting moderate correlations and Co 3d electrons displaying weaker correlations. Pronounced conduction-4f (c-f) hybridization is observed alongside an orbital-selective metal–insulator dichotomy. CeCoSi2 displays a noninteger Ce 4f valence with significant 4f0, 4f1, and 4f2 contributions. The lattice-electron coupling asymmetry indicates that Ce 4f localization drives the lattice expansion, while Co 3d delocalization induces lattice contraction. These findings provide insights into the physics of rare-earth intermetallics and offer potential implications for materials design.