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A field-induced novel phase transition, from even- to odd-parity superconducting pairing state, has recently been observed in CeRh₂As₂ [1].  The question why this is the case in CeRh₂As₂ and not in other materials remains to be answered.  In this talk, based on DFT calculations and supporting symmetry arguments, we address question through an examination of the normal state properties, including the Fermi surface arising from renormalized 4f bands and electron spin polarization near the chemical potential of CeRh₂As₂ [2].