We revisit the well-known problem of density of states in the impurity
band tails using a random-matrix theory approach. As a model for the
system, we consider a ''tridiagonal'' random matrix with diagonal elem
ents taken to be independent and Gaussian distributed. We solve the mo
del in one dimension using a recursive method in the large-N (number o
f sites) limit. We obtain an analytical expression that agrees with Li
fshitz-Halperin-Lax results for energy dependence of the density of st
ates as a stretched exponent of E(3/2) in the asymptotic regime.