A dispersion minimizing subgridding finite difference scheme for the Helmholtz equation with PML

In this paper, we present a dispersion minimizing subgridding finite difference scheme for solving the Helmholtz equation with perfectly matched layer (PML) in the two dimensional domain, which is a second order scheme and pointwise consistent with the equation. Subgrids are used to discretize the computational domain, and a refined choice strategy based on minimizing the numerical dispersion is proposed for choosing weight parameters for transitional nodes. Numerical experiments are given to illustrate that the newly proposed schemes can produce highly accurate seismic modeling results with enhanced efficiency, compared to uniform grids.