We perform a self-consistent calculation of resonant tunneling diode (RTD) I-V characteristics including optical phonon scattering. The self-consistency is obtained by solving the Schrödinger equation and Poisson’s equation iteratively with the Thomas-Fermi approximation used for the device contact regions. For evaluation of phonon-assisted current density, the optical phonon scattering in the quantum well is modeled using the optical model potential. Electron transverse momentum is also incorporated. The calculated current and electron wavefunction illustrate the optical model and effects of the phonon scattering on the current transport. The I-V characteristics we obtain from the model calculation are in good agreement with experimental results. This work manifests the importance of including self-consistency, optical phonon scattering, and electron transverse momentum in modeling realistic RTD structures.