Why are we choosing N as an even number? Let nf denote the topmost filled energy level, where we start filling the1) and continue filling higher levels with elec-trons until all N electrons are accommodated. It is convenient to supposethe value of forlevels from the bottom (nthatN is an even number. The condition 2n pN determines nF,the uppermost filled level.The Fermi energy er is defined as the energy of the topmost filled levelin the ground state of the N electron system. By (3) with n = nF we have in onedimension:h2 (NT2m \ 2LEf(4)2m

Let nf denote the topmost filled energy level, where we start filling the levels from the bottom (n = 1) and continue filling higher levels with elec- trons until all N electrons are accommodated. It is convenient to suppose that N is an even number. The condition 2nr the uppermost filled level. The Fermi energy ep is defined as the energy of the topmost filled level in the ground state of the N electron system. By (3) with n = nf We have in one N determines nF, the value of n for dimension:

Let nf denote the topmost filled energy level, where we start filling the levels from the bottom (n = 1) and continue filling higher levels with elec- trons until all N electrons are accommodated. It is convenient to suppose that N is an even number. The condition 2nr the uppermost filled level. The Fermi energy ep is defined as the energy of the topmost filled level in the ground state of the N electron system. By (3) with n = nf We have in one N determines nF, the value of n for dimension: