  In the heavy fermion materials, the characteristic energy scales of many
exotic strongly correlated phenomena (Kondo effect, magnetic order,
superconductivity, etc.) are at milli-electron-volt order, implying that the
heavy fermion materials are surface sensitive. Here, we investigate the
electronic structures for Si- and Ce-terminated surfaces of CeRh$_2$Si$_2$ by
first-principles methods. Our research reveals three notable impacts of surface
effects on electronic structures, which are consistent with recent
angle-resolved photoemission spectroscopy (ARPES) experiments. Firstly, the
relaxation of surface crystal structures changes the relative position of Fermi
level, adjusts the dispersion of bands and enhances the Kondo resonance.
Secondly, the decrease of the hybridization between the Ce-4$f$ and conduction
electrons in the surface layer leads to a weaker Kondo resonance peak and the
shift of spin-orbit bands. Thirdly, the variation of crystal electric field
around surface Ce atoms affects the splitting of Kondo resonance peaks, and
also pushes down the lower-Hubbard bands of surface 4$f$ electrons. Moreover,
we find the characteristic of bulk's lower-Hubbard bands, which was overlooked
in previous works. Our investigation suggests that these surface effects are
potentially important and highlighted in the future researches on properties of
strongly correlated materials.
