The electromagnetic properties of a heavy fermion YbAgGe are investigated by electronic band structure calculation based on the density functional theory within LDA, LDA+U, and fully relativistic schemes. The electronic structure with the spin-orbit interaction and on-site Coulomb potential for the Yb-derived 4f orbitals was calculated for the correct ground state of YbAgGe. The exchange interactions between local f electrons and conduction electrons play an important role in the heavy fermion characters of them. When the Coulomb potential is added to the Yb 4f orbitals, the degeneracy between the different f orbitals is lifted and they are split into lower Hubbard bands and upper Hubbard bands. The fully relativistic band structure scheme shows that spin-orbit coupling splits the 4f states into two manifolds, the  and the  multiplet.

YbAgGe, electronic structure.