“…Comparing with FDTD method, the pseudospectral time domain (PSTD) method [Fornberg, 1996] has some potential merits in numerical computation, e.g., PSTD requires only two grids for a wavelength [Fornberg, 1996;Liu, 1997], while FDTD needs at least eight grids to achieve the same precision; the spatial derivatives are calculated by fast Fourier transform (FFT) in PSTD, leading to neglecting numerical dispersion due to its high precision, while strong numerical dispersion is expected for FDTD as long as the grid is not fine enough. Thus, PSTD showed potential applications in various disciplinary because it takes much less computer memory and computation time to achieve the same precision as FDTD [Fornberg, 1996;Liu and Fan, 1999;Wang et al, 2001;Liu et al, 2006;Li et al, 2009].…”