Improvements of the equation of motion technique for disordered systems

The equation of motion technique for the calculation of dynamical properties of large disordered systems is reconsidered and two improvements are proposed. Several procedures for the numerical integration of systems of second‐order differential equations are discussed and one particular efficient integration formula is selected. A modified cosine transformation for finite integration intervals is presented, which gives a positive, bell‐shaped function as a representation of the δ‐function instead of sin (ωT)/ωT. This allows an easier discussion of highly structured spectra. The results are demonstrated by a simple example.