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Particle-Mesh code for cosmological simulations

Anatoly Klypin and Jon Holtzman

Department of Astronomy, New Mexico State University

Las Cruces, NM 88001



Particle-Mesh (PM) codes are still very useful tools for testing predictions of cosmological models in cases when extra high resolution is not very important. We release for public use a cosmological PM N-body code. The code is very fast and simple. We provide a complete package of routines needed to set initial conditions, to run the code, and to analyze the results. The package allows you to simulate models with numerous combinations of parameters: open/flat/closed background, with or without the cosmological constant, different values of the Hubble constant, with or without hot neutrinos, tilted or non-tilted initial spectra, different amount of baryons.

Routines are included to measure the power spectrum and the density distribution function in your simulations, and a bound-density-maxima code for halo finding. We also provide results of test runs. A simulation with 2563 mesh and 1283 particles can be done in a couple of days on a typical workstation (about 70Mb of memory is needed). To run simulations with 8003 mesh and 2563 particles one needs a computer with 1Gb memory and 1Gb disk space. The code has been successfully tested on an HP workstation and on a Sun workstation running Solaris, but we expect it should work on other systems.

The package can be downloaded from . A PostScript version of this manual can be obtained from We provide this tool as a service to the astronomical community, but we cannot guarantee results. If you download the package or are generally interested, please register your name and email address here so we can notify you if we add additional features, find any bugs, etc.:


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Equations and dimensionless variables
Scheme of integration
Format of data
Initial conditions: CDM and CHDM models
Finding Halos with Bound Density Maxima code
How to compile and run the code
How to set initial conditions
Models without massive neutrinos
Models with massive neutrinos
Initial conditions for arbitrary initial power spectra
How to run the PM code
How to get coordinates and velocities of particles
How to get power spectrum and density distribution
How to find halos using the Bound-Density-Maxima code

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Next: Introduction
Jon Holtzman