Particle-mesh simulations of clustering in cosmology

Recently developed techniques are used to suggest a prescription for building an optimal particle-mesh or particle-in-cell code. This involves a judicious choice of the Green's function for solving the Poisson equation. Potential difficulties associated with this prescription are considered, and arguments are presented to suggest that these should not be serious. It is also demonstrated that the onset of nonlinearity is not significantly altered by numerical effects. Finally, a quantitative measure is provided for the accuracy with which short scales can be probed. It is applied to various existing codes