GridSPT: Grid-based calculation for perturbation theory of large-scale
  structure
  Perturbation theory (PT) calculation of large-scale structure has been used
to interpret the observed non-linear statistics of large-scale structure at the
quasi-linear regime. In particular, the so-called standard perturbation theory
(SPT) provides a basis for the analytical computation of the higher-order
quantities of large-scale structure. Here, we present a novel, grid-based
algorithm for the SPT calculation, hence named GridSPT, to generate the
higher-order density and velocity fields from a given linear power spectrum.
Taking advantage of the Fast Fourier Transform, the GridSPT quickly generates
the nonlinear density fields at each order, from which we calculate the
statistical quantities such as non-linear power spectrum and bispectrum.
Comparing the density fields (to fifth order) from GridSPT with those from the
full N-body simulations in the configuration space, we find that GridSPT
accurately reproduces the N-body result on large scales. The agreement worsens
with smaller smoothing radius, particularly for the under-dense regions where
we find that 2LPT (second-order Lagrangian perturbation theory) algorithm
performs well.
