2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99206We study crystal dynamics in the harmonic approximation. The atomic masses are weakly disordered, in the sense that their deviation from uniformity is of order epsilon^(1/2). The dispersion relation is assumed to be a Morse function and to suppress crossed recollisions. We then prove that in the limit epsilon to 0 the disorder averaged Wigner function on the kinetic scale, time and space of order epsilon^(-1), is governed by a linear Boltzmann equation.71 pages, 3 figuresMathematical PhysicsDisordered Systems and Neural Networks82D30; 80M40; 74J20text