Stoneham [Phys. Rev. B 1, 3966 (19'70)]. A notational error might cause confusion. In Eq. (3.6), X", should read R"" the potential associated with the pth interstice (the division of K", into terms associated with different interstices is to some extent arbitrary but does not affect subsequent steps). Equations after (3.6) should all contain &&+X", rather than X", alone. The proper terms were used throughout the actual calculations, so the conclusions are not affected. A final point is that the integrand in Eq. (A6) should contain x rather than xa as printed. The related formulas are correct.

No abstract

No abstract

No abstract

No abstract