For the Lanthanides we present a total energy versus volume graph for La which shows the correct ground state as dhcp. As it is shown in the energy bands and DOS figures the f-bands are positioned above the Fermi level for La. As we examine the energy bands and DOS for the rest of the elements (except for Lu for which we show total energies for fcc and bcc with a standard method) in this row we note that Ef is located inside the f-bands and finally in Yb and Lu lies above the f-bands. The, at-least, partially occupied f-bands in these materials present a serious difficulty in determining the equilibrium volume and structure using standard density functional theory. We have found that the only way to calculate a reasonable equilibrium volume for these materials is to push the f-electrons into the core and use only s- and d- electrons in the valence . We demonstrate this for Ce, Pr, Nd, Pm, and Sm where the equilibrium fcc, bcc and sc volumes are predicted by forcing the f-bands into the core. For Eu, we show fcc, bcc, as well as hcp equilibrium volumes using the same method. For the rest of the elements in this row, which are mostly existing in hcp lattice, we present energy bands and DOS for the equivalent fcc volume to show trends.