Bound states of the one-dimensional Dirac equation for scalar and vector double square-well potentials

We have analytically studied bound states of the one-dimensional Dirac equation for scalar and vector double square-well potentials (DSPs), by using the transfer-matrix method. Detailed numerical calculations of the eigenvalue, wave function and density probability have been performed for the three cases: (1) vector DSP only, (2) scalar DSP only, and (3) scalar and vector DSPs with equal magnitudes. We discuss the difference and similarity among results of the cases (1)-(3) in the Dirac equation and that in the Schr"{o}dinger equation. Motion of a wave packet is calculated for a study on quantum tunneling through the central barrier in the DSP.