Evidence of decisive effect of crystal-field splitting in spin-state transition

Abstract

Based on the first-principle calculations for 3D Hofmann-like spin-crossover (SCO) compound [Fe(C₄H₄N₂){Pt(CN)₄}], the discrepancy of transition mechanism is clarified with quantitatively distinguishable evidence of second order phase transition. It shows that the stretch around 0.2 Å of Fe-N bond length leads to the continuous structure expansion, as the energy splitting ΔE _HL between low-spin and high-spin states reduces from 2.554 2 eV to −0.327 8 eV, and the crystal-field splitting (CFS) is reduced from 1.845 8 eV to 0.420 8 eV meanwhile. A physics image relating the calculations results with CFS in the frame of ligand-field theory is presented, which manifests that CFS is a necessary parameter to be introduced directly in the theory of spinstate transition.

Keywords

spin-crossover / crystal-field splitting / first-principle calculations

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