Weyl formula for multi-quasi-elliptic operators. of Schrödinger type

In this work we consider a general class of Schr?dinger type operators, associated with multi-quasi-elliptic symbols. We give a precise estimate of the remainder of the so-called Weyl asymptotic formula for the eigenvalues of these operators. In order to reach our aim, we use the Weyl–H?rmander calculus, with locally temperate metrics and weights, and interpolation techniques. Received: February 14, 2000; in final form: October 29, 2000?Published online: July 13, 2001