Supplementary material

Separable crystal potentials

B. Kollmitzer and P. Hadley
Institute of Solid State Physics, Graz University of Technology, Graz, Austria

The density of states at the Fermi energy and its derivative

The thermodynamic quantities of a metal such as the entropy or the specific heat can be estimated using the Sommerfeld expansion. This approximation requires a knowledge of the density of states at the Fermi energy D(E_F) and the derivative of the density of states at the Fermi energy D'(E_F). These two quantities are plotted below for all of the 10000 separable potentials that were considered and for electron densities from n = 1 electron/primitive cell to n = 10 electrons/primitive cell. It was not possible to determine the density of states at the Fermi energy reliably in the crosshatched regions.

Electron density n = 1 electron/primitive cell

Electron density n = 2 electrons/primitive cell

Electron density n = 3 electrons/primitive cell

Electron density n = 4 electrons/primitive cell

Electron density n = 5 electrons/primitive cell

Electron density n = 6 electrons/primitive cell

Electron density n = 7 electrons/primitive cell

Electron density n = 8 electrons/primitive cell

Electron density n = 9 electrons/primitive cell

Electron density n = 10 electrons/primitive cell