Data and Das [S. Datta and B. Das, Appl. Phys. Lett. 56, 665 (1990)] proposed an electronic analog to the optoelectronic modulator which would employ spin injection from a ferromagnet into a semiconductor. We investigate the ferromagnet–semiconductor system consisting of the Heusler alloy [formula omitted] and the semiconductor InAs. Using a full-potential electronic structure code with a basis set of Slater-type orbitals, we have calculated the band structure of [formula omitted] We calculate the spin polarization for each atom. It resides primarily on the Mn atom (3.51), with a small moment (0.31) on the Ni. Interestingly, In has a very small moment (−0.04), which is antiferromagnetically coupled to the other atoms. Using a simple model, we estimate the transmittance of minority spins in three high-symmetry directions.