3. Rectangular box. In the rectangular box of Fig. 39-14, fitting an electron wave
to the box’s widths Lx, Ly, and Lz requires the three quantum numbers nx, ny,
and nz. Thus, any electron confined to the trap must have certain values for
these three quantum numbers, and its quantum number ms can be either or
; so now there are four quantum numbers. According to the Pauli exclusion
principle, two electrons confined to the trap must have different values for at
least one of those four quantum numbers.