Variable fillings

An important test case of the pseudopotential software which we shall develop is the case of an isolated atom of Ge. The valence electrons of Ge have the configuration 4s$^2$4p$^2$. The 4p$^2$ means that the three $p$ states share two electrons equally. This means that the fillings vector $\vec f$ should be f=[2;2/3;2/3;2/3]. Our current software, however, assumes constant fillings, f=[2;2;2;...]. We must modify the current DFT software to include the appropriate general expressions.