There are three criterions determining the state of electron in multielectron
atoms. (1) Pauli exclusion principle, (2) Energy minimization
principle, and (3) Hund rules. Fermi energy is different due to the difference
in species and structure of atomaswell as numbers of primary and
secondary quantum. A systemhas higher Fermi energy are easier to lose
its electron outside, which means that metal will be easily corroded.
CASTEP module in Materials studio program was used to investigate
Fermi energy of the tin-containing steel (α-Fe standard cell, add C in
atomic structure and 2 × 2 × 2 supercell. C occupies only one set of
octahedral gap of the Fe sub lattice, and some Fe atoms of the α-Fe
cell are substituted by solid solution element tin).