EN
Theory of shallow donor in III-V semiconductors in the presence of magnetic field is reinvestigated. Considerations are performed within the 3-level Kane model. In order to avoid singularities caused by the Coulomb potential we divide it into short- and long-range components. The latter one is the slowly varying potential and contrary to the Coulomb potential it satisfies all demands for envelope function equation. The short-range part is contributing to a chemical shift. Calculation of energies of two possible spin states of ground donor level are then performed using variational method.