  This paper proposes a new simultaneous terahertz (THz) information and power
transfer (STIPT) system, which is assisted by reconfigurable intelligent
surface (RIS) for both the information data and power transmission. We aim to
maximize the information users' (IUs') data rate while guaranteeing the energy
users' (EUs') and RIS's power harvesting requirements. To solve the formulated
non-convex problem, the block coordinate descent (BCD) based algorithm is
adopted to alternately optimize the transmit precoding of IUs, RIS's reflecting
coefficients, and RIS's coordinate. The Penalty Constrained Convex
Approximation (PCCA) Algorithm is proposed to solve the intractable
optimization problem of the RIS's coordinate, where the solution's feasibility
is guaranteed by the introduced penalties. Simulation results confirm that the
proposed BCD algorithm can significantly enhance the performance of STIPT by
employing RIS.
