2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/20429This paper has been withdrawn by the authors. A more complete treatment of the bandstructure effects is forthcoming.Manuscript withdrawn by the authorsMesoscale and Nanoscale PhysicsQuantum PhysicsSilicon conduction-band effects on shallow donor wavefunctions and donor-pair exchange: An {\it ab initio} theorytext