The origin of the flat band diagram

1. Deduce and sketch the flat band diagram for FeO crystal with good estimates for energy differences between band edges and 3d energy levels or bands. First, sketch the electron energy vs. separation distance as N number of iron and oxygen atoms come together to form FeO crystalline solid. Use an accurate energy scale on your drawing. Start from the following discrete electron energy levels for widely separated atoms. Take binding energies (referenced to vacuum level) as: O 2s = -28.7 eV; O 2p = -13.6 eV; Fe 3d = -9.3 eV; Fe 4s = -7.9 eV. Show reasonable electron energy band formation and indicate the equilibrium separation distance illustrating the origin of the flat band diagram.

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