在温度0 K，且一个原子不被授与能量时，最高层电子所在的能阶，就是费米能阶，而能量就是费米能量。
The Fermi Energy, which is synonymous with the electron chemical potential at T=0, represents the energy level that the next electron into the system must have, to be at the lowest possible freely-available state.
The Fermi level is the level at which the electron occupancy is 0.5 (or the highest filled level at 0 K).
The Fermi energy is the energy of the electrons in that level.
The highest energy level in the crystal that can remain populated by electrons at a temperature of Absolute Zero.
