Electron Energy DensityThe behavior of electrons in solids depends upon the distribution of energy among the electrons: Since electrons are fermions, the distribution function is the FermiDirac distribution This distribution determines the probability that a given energy state will be occupied, but must be multiplied by the density of states function to weight the probability by the number of states available at a given energy. The determination of how many ways there are to obtain an energy in an incremental energy range dE can be approached with the quantum mechanical particle in a box. The energy for an infinite walled box is
The energy can be expressed in terms of R and vice versa. The nspace associated with the particleinabox involves only positive values of n, so the volume must be divided by 8. It then must be multiplied by 2 to account for the two possible spin values of the electron. The number of values is then The number of states per unit volume is The final density of states as a function of energy is then the derivative of this population with respect to energy This represents the number of electron states per unit volume per unit energy at energy E. This energy density is a factor in many of the electrical properties of solids. Note that the result is independent of the dimension L which was chosen above, showing that the expression can be applied to the bulk material.

Index Quantum statistics concepts References Rohlf Sec 12.6 Richtmyer, et al. Ch. 5  
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