a strong mixing of geometric configurations would occur and would spoil the crystal-like picture. However, this is not true mainly due to the quantum constraints as we shall see later.

\(ii) [**Uniform rotation**]{} .

 Let us consider first a classical model system of two rotating homocentric rings. the outer ring has ($b\leq r\leq a$), while the inner ring has ($d\leq r\leq c$ , and $\ $c$\leq b$).  Let the angular momentum, the moment of inertia and the angular velocity of the outer (inner) ring be $%
l_{out}$, $I_{out}$ and $\omega _{out}$ ( $l_{in}$, $I_{in}$ and  $\omega
_{in}$), respectively. The total angular momentum $L=l_{out}+l_{in}=I_{out}%
\omega _{out}+I_{in}\omega _{in}$ , and the total rotation energy $T=\frac{1%
}{2}(I_{out}\omega _{out}^{2}+I_{in}\omega _{in}^{2})$ . Now, let us ask how the $\omega _{out}$ and $\omega _{in}$ would be chosen so that $T$ is minimized under the condition that $L$ is conserved? The answer is simply $%
\omega _{out}=\omega _{in}=L/(I_{out}+I_{in})=L/I$. This fact implies that if the two rings are rotating with the same angular velocity, the rotation energy can be reduced. Although this point is viewed from classical mechanics, however the first-states of a quantum mechanic system would do its best to lower the energy, thus they would pursue 