Multiorbital Two-Band Landau–Fermi Liquidness of 1 <i>T</i> -Ti(Se,Te) ₂ van der Waals Crystals

Normal-state Landau-Fermi-liquid (LFL) behavior is widely regarded as a prerequisite for low-temperature superconductivity in 1<i>T</i>-Ti<i>X</i>₂ (<i>X</i> = Se, Te) van der Waals (vdW) crystals. Clarifying this role requires a microscopic description of how local electron correlations and Ti-chalcogen covalence cooperate to shape the low-energy electronic structure in the noncharge-density-wave (non-CDW) regime. In the present work, we employ density functional theory combined with dynamical mean-field theory (DFT + DMFT) to investigate an extended multiorbital (MO) two-band Hubbard model specifically constructed for these transition-metal dichalcogenides. The calculations reveal an emergent LFL metal stabilized by dynamical intra- and interorbital correlations in the Ti-based manifold, while the chalcogen 4p/5p states remain comparatively rigid against changes in interaction strength. This orbital-selective reconstruction leads to a strongly anisotropic renormalization of the Ti-3d sector, which we identify as a key ingredient for the superconducting phase diagram of 1<i>T</i>-Ti<i>X</i>₂. Beyond demonstrating the capability of DFT + DMFT to capture such MO correlation effects, our results show that proximity to a correlated LFL state naturally accounts for the distinct low-temperature transport responses of the Se and Te compounds, where modest variations in interaction-to-bandwidth ratio and orbital occupancy drive markedly different sensitivities to external tuning parameters such as pressure, doping, or gating.