Locally noncentrosymmetric structures in crystals are attracting much attention owing to emergent phenomena associated with the sublattice degree of freedom. The newly discovered heavy fermion superconductor ${\mathrm{CeRh}}_2{\mathrm{As}}_2$ is considered to be an excellent realization of this class. Angle-resolved photoemission spectroscopy experiments recently observed low-energy spectra of electron and hole bands and characteristic Van Hove singularities, stimulating us to explore the electronic correlation effect on the band structure. In this Letter, we theoretically study the electronic state and topological superconductivity from first principles. Owing to the Coulomb repulsion $U$ of Ce $4f$ electrons, the low-energy band structure is modified in accordance with the experimental result. We show that Fermi surfaces change significantly from a complicated three-dimensional structure to a simple two-dimensional one. Fermi surface formulas for one-dimensional ${\mathbb{Z}}_2$ invariants in class D indicate topological crystalline superconductivity protected by the glide symmetry in a broad region for $U$. The classification of superconducting gap structure reveals the topologically protected excitation gap and node. Our findings of the correlation-induced evolution of electronic structure provide a basis to clarify the unusual phase diagram of ${\mathrm{CeRh}}_2{\mathrm{As}}_2$ including superconductivity, magnetic order, and quadrupole density wave, and accelerate the search for topological superconductivity in strongly correlated electron systems.

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• Superconducting gap
• Superconductivity
• Topological phases of matter
• Heavy-fermion systems
• Strongly correlated systems
• Topological superconductors
• First-principles calculations
• Group theory