Potassium metal has one conduction electron per atom

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Free electrons, energy bands and electronic structure · Free electrons, energy bands and electronic structure

Solid State Physics, Ch The degenerate electron gas, finished

Problem

Potassium metal has one conduction electron per atom, electron density n=1.40×1028 m−3n=1.40\times10^{28}\,\mathrm{m^{-3}} and Fermi energy EF=2.12 eVE_F=2.12\,\mathrm{eV}. Its measured bulk modulus is 2.81 GPa2.81\,\mathrm{GPa}. ((a)) Estimate the T=0T=0 degeneracy pressure of the conduction electrons, P=25nEFP=\tfrac25nE_F. ((b)) Estimate the corresponding degeneracy bulk modulus B=23nEFB=\tfrac23nE_F. ((c)) Compare the estimate with the measured bulk modulus, quoting the ratio, and comment on what the comparison shows for an alkali metal.

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