| Abstract: | The strong-coupling approximation is investigated in a model one-dimensional  potential. It is shown that even for large values of the overlap integrals S = 0.5 the approximation gives good results when a sufficiently large number of neighbors is taken into account. Otherwise, the approximation can give spurious extrema in the density of states. A modified strong-coupling method is formulated having considerable advantage over the usual method.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 27–30, March, 1975. |
