It is shown that for the screened Coulomb potential and isotropic harmonic
oscillator, there exists an infinite number of closed orbits for suitable a
ngular momentum values. At the aphelion (perihelion) points of classical or
bits, an extended Runge-Lenz vector for the screened Coulomb potential and
an extended quadrupole tensor for the screened isotropic harmonic oscillato
r are still conserved. For the screened two-dimensional (2D) Coulomb potent
ial and isotropic harmonic oscillator, the dynamical symmetries SO3 and SU(
2) are still preserved at the aphelion (perihelion) points of classical orb
its, respectively. For the screened 3D Coulomb potential, the dynamical sym
metry SO4 is also preserved at the aphelion (perihelion) points of classica
l orbits. But for the screened 3D isotropic harmonic oscillator, the dynami
cal symmetry SU(2) is only preserved at the aphelion (perihelion) points of
classical orbits in the eigencoordinate system. For the screened Coulomb p
otential and isotropic harmonic oscillator, only the energy (but not angula
r momentum) raising and lowering operators can be constructed from a factor
ization of the radial Schrodinger equation.