Let Hn be the Heisenberg group and Q=2n+2 be its homogeneous dimension.
In this paper, we consider the Schr ¨odinger operator −∆Hn +V, where ∆Hn is
the sub-Laplacian and V is the nonnegative potential belonging to the reverse H ¨older
class Bq1for q1 ≥ Q/2. We show that the operators T1 = V(−∆Hn +V)−1 and T2 =
V1/2(−∆Hn +V)−1/2 are both bounded from H1L(Hn) into L1(Hn). Our results are
also valid on the stratified Lie group.