Calculate the carrier concentration at a given Fermi level

[scott-maddox]

• put in a new calculations or calculators module?
• Begin by using approximations, then decide if the assumptions are met?
  • approximations:
    1. non-degenerate limit
    2. degenerate limit
    3. iteratively solved approximation for a parabolic band
    4. full integration for a parabolic band?
    5. full integration including satellite valleys
    6. full integration for a Kane band
    7. full integration a Kane band and satellite valleys
  • The correct implementation should be picked automatically by default, but the various implementations should also be callable directly for advanced users
  • Strained layers?
• require numpy only if neither non-degenerate nor degenerate limits apply?
• provide instancing to cache the density of states so that multiple consecutive calculations can be sped up