  The interplay between the spin-orbit and Zeeman interactions on a spinful
Su-Schrieffer-Heeger model is studied based on an InAs nanowire subjected to a
periodic gate potential along the axial direction. It is shown that a
nontrivial topological phase can be achieved by regulating the
confining-potential configuration. In the absence of the Zeeman field, we prove
that the topology of the chain is not affected by the Rashba spin-orbit
interaction due to the persisting chiral symmetry. The energies of the edge
modes can be manipulated by varying the magnitude and direction of the external
magnetic field.Remarkably, the joint effect of the two spin-related
interactions leads to novel edge states that appear in the gap formed below the
anti-crossing of the bands of an open spinful dimerized chain, and can be
merged into the bulk states by tilting the magnetic-field direction.
