The quantum harmonic-parabola system, whose potential energy is the negativ
e harmonic potential, is analyzed and applied to the cases of a quantum wel
l, barrier, and periodic lattices. The eigenstate of the quantum Hamiltonia
n of the harmonic-parabola system is obtained. It is shown that any functio
n may be expanded in terms of the eigenfunctions of the system in a finite
interval, and the propagator of the system can be obtained from the eigenfu
nctions. The energy eigenvalues, uncertainty, and probability density for t
he first few states are treated for the infinite harmonic-parabola well. Th
e energy eigenvalues and their enumeration, the energy band, and the probab
ility density for the first few states are obtained for a well composed of
the parabola and constant potentials. The transmission coefficients and eac
h potential interval dependence are determined for this well and the barrie
r of the parabola-constant potential structure. Periodic lattices composed
of the parabola potential and parabola-constant potentials are constructed,
and their dispersion relations, energy states, and bands are obtained.