**Fermi Surface for Tight Binding Models**

These are Fermi surfaces for nearest neighbor tight binding models
arrising from a single s-level. They were produced in Mathematica.
Here is a sample code courtesy of Bradley Nartowt:

ContourPlot3D[ -2 Cos[kx] -2 Cos[ky] -2 Cos[kz] == 2.8, {kx, -\[Pi], \[Pi]}, {ky, -\[Pi], \[Pi]}, {kz, -\[Pi], \[Pi]}]

**Simple Cubic**

E = -2 cos(k_{x}a) -2 cos(k_{y}a) -2 cos(k_{z}a)

**Body Centered Cubic**

E = -8 cos(k_{x}a/2) cos(k_{y}a/2) cos(k_{z}a/2)

BCC, E=-7 |
BCC, E=-6 |
BCC, E=-5 |
BCC, E=-4 |
BCC, E=-3 |

BCC, E=-2 |
BCC, E=-1 |
BCC, E= 0 |
BCC, E= 1 |
BCC, E= 2 |

BCC, E= 3 |
BCC, E= 4 |
BCC, E= 5 |
BCC, E= 6 |
BCC, E= 7 |

**Face Centered Cubic**

E = -4 cos(k_{x}a/2) cos(k_{y}a/2)
-4 cos(k_{y}a/2) cos(k_{z}a/2)
-4 cos(k_{z}a/2) cos(k_{x}a/2)

FCC, E = -11 |
FCC, E = -10 |
FCC, E = -9 |
FCC, E = -8 |

FCC, E = -7 |
FCC, E = -6 |
FCC, E = -5 |
FCC, E = -4 |

FCC, E = -3 |
FCC, E = -2 |
FCC, E = -1 |
FCC, E = 0 |

FCC, E = 1 |
FCC, E = 2 |
FCC, E = 3 |
FCC, E = 3.9 |