It is shown that in the absence of central cell corrections, anisotropy of the donor envelope functions is the most important factor in determining the change in the metal-insulator transition density as a function of uniaxial stress in $n$-doped many-valley semiconductors. Quantitative agreement is obtained with experimental results for antimony-doped germanium, and a prediction made for the corresponding case in silicon.

• Received 6 May 1981

DOI:https://doi.org/10.1103/PhysRevB.24.3630