Free Electron Gas Model
In the free electron model the valence electrons roam freely (zero force) inside the metal but find a confining potential step at the boundary of the metal. In the system's ground state, states with energy less than the Fermi Level are occupied, and states above the Fermi Level are not occupied. The energy required to liberate an electron in the Fermi Level is the work function. If, as in the diagram right, we define the Fermi Energy from the bottom of the well, the results reported in the Wiki page Fermi energy are applicable. However, usually the Fermi energy is referenced to energy zero: that of the lowest energy electron free of the metal. In that case the Fermi energy would have a negative value (i.e., the Fermi Level lies below those of escaped electrons) (but see below).
Read more about this topic: Work Function
Famous quotes containing the words free, gas and/or model:
“Without free, self-respecting, and autonomous citizens there can be no free and independent nations. Without internal peace, that is, peace among citizens and between the citizens and the state, there can be no guarantee of external peace.”
—Václav Havel (b. 1936)
“When we can drain the Ocean into mill-ponds, and bottle up the Force of Gravity, to be sold by retail, in gas jars; then may we hope to comprehend the infinitudes of man’s soul under formulas of Profit and Loss; and rule over this too, as over a patent engine, by checks, and valves, and balances.”
—Thomas Carlyle (1795–1881)
“The best way to teach a child restraint and generosity is to be a model of those qualities yourself. If your child sees that you want a particular item but refrain from buying it, either because it isn’t practical or because you can’t afford it, he will begin to understand restraint. Likewise, if you donate books or clothing to charity, take him with you to distribute the items to teach him about generosity.”
—Lawrence Balter (20th century)