We study a quantum system of p commuting matrices and find that such a
quantum system requires an explicit curvature dependent potential in its
Lagrangian for the system to have a finite energy ground state. In contrast it
is possible to avoid such curvature dependence in the Hamiltonian. We study the
eigenvalue distribution for such systems in the large matrix size limit. A
critical r\^ole is played by p=4. For p≥4 the competition between
eigenvalue repulsion and the attractive potential forces the eigenvalues to
form a sharp spherical shell.Comment: 17 page