Some Estimates of Schrödinger-Type Operators with Certain Nonnegative Potentials

where the potential V belongs to Bq1 for q1 ≥ n/2. We are interested in the L boundedness of the operator∇4H−1, where the potential V satisfies weaker condition than that in 5, Theorem 1, 2 . The estimates of some other operators related to Schrödinger-type operators can be found in 2, 5 . Note that a nonnegative locally L integrable function V on R is said to belong to Bq 1 < q < ∞ if there exists C > 0 such that the reverse Hölder inequality ( 1 |B| ∫