Fermi wave vector defined

A weak 2kF diffuse x-ray scattering [58], seen only at low temperature, confirms that p = in this salt and indicates that the Fermi wave vector is rather well defined despite structural cation disorder. A stronger 4kF scattering [58] observed from 25 K to 300 K is an indication of large Coulomb effects in this salt, with U t, in agreement with other known magnetic and thermopower data [57,58]. 

The energy of the conduction electrons is given by h2k2/2 x, where k is the wave vector number and p, is the effective mass of the electron-nucleus. In a real space of Cartesian coordinates k = [kx, ky, fcj, a Fermi sphere can be constructed with radius k = (2 lE )x 2/h. The shape of this sphere is a clearly defined by the electrical properties of the metal. The current density obeys the change in the occupancy of states near the Fermi level, which separates the unfilled orbitals in the metal from the filled ones in the linear momentum space p = hk. 

The next problem is the band filling and the position of the Fermi level Ep at zero Kelvin. We have seen that the supposed uniform degree of ionicity p can be defined from the stoichiometry (cf. Table 2). It allows us to define the number of charge carriers per molecule, (Ng/N), and therefore, from the energy band dispersion E(k), the wave vector kp which is associated with the Fermi level position. It follows that every orbital can hold two electrons ... 

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