  Spin-orbit coupling in chiral materials can induce chirality-dependent spin
splitting, enabling electrical manipulation of spin polarization. Here, we use
first-principles calculations to investigate the electronic states of chiral
one-dimensional (1D) semiconductor InSeI, which has two enantiomorphic
configurations with left- and right-handedness. We find that opposite spin
states exist in the left- and right-handed 1D InSeI with significant spin
splitting and spin-momentum collinear locking. Although the spin states at the
conduction band minimum (CBM) and valence band maximum (VBM) of 1D InSeI are
both nearly degenerate, a direct-to-indirect bandgap transition occurs when a
moderate tensile strain ($\sim$4%) is applied along the 1D chain direction,
leading to a sizable spin splitting ($\sim$0.11 eV) at the CBM. These findings
indicate that 1D InSeI is a promising material for chiral spintronics.
