The energy "E"i is the ionization energy corresponding to the chosen atomic orbital and "U" is the energy shift of the orbital as a result of the potential of neighboring atoms. The formula_67 elements, which are the Slater and Koster interatomic matrix elements, are the bond energies formula_68. In this one dimensional s-band model we only have formula_69-bonds between the s-orbitals with bond energy formula_70. The overlap between states on neighboring atoms is "S". We can derive the energy of the state formula_71 using the above equation: