Models without massive neutrinos

A range of initial spectra which have been computed by our Boltzmann code and fit with our fitting function (ea.20) are available. The fitting parameters are tabulated in the file cdm.fit. You will need to look in this file and determine the line number of the model which you are interested in. The first program (PMmodels) will ask to give you the following parameters:

• Name of a file where it writes parameters of the model and normalized power spectra.
• $\sigma_{8}^{}$ = rms density perturbation in a sphere of radius 8h ^{- 1}Mpc and the slope of the power spectrum at long
• Line number in the file cdm.fit
• Size of the simulation box, number of particles in 1D, and the redshift at which you would like to start your code (or to get the power spectrum).
• The program will ask you if you need to have a file with all input parameters needed to set initial conditions. If you need the file, answer ``Yes'', and it will create file InStart.dat, which you will give as input to the second code PMstartCDM. It will also ask you few questions needed to produce the file. If you answer ``No'', the code finishes its work by creating the file with the name you gave it in the first line. The file has parameters of the model (all $\Omega$ 's, the Hubble constant, the age of the universe, growth rate of density $\delta$ , and d (ln $\delta$)/d (ln a ) at different redshifts. It also gives the bulk velocity of a sphere of radius 50h ^{- 1}Mpc and normalized power spectra of dark matter at redshift zero ( a = 1 ) and at the redshift you provided.
• If you answered ``Yes'' for the previous question (you needed to have an input file for PMstartCDM), you will be asked to provide the following information:
  • A string of up to 45 characters (``header''). The header is not used for simulations, but it is useful to label your simulation. You can provide any information you want. This header will stick to your run. All files with snapshots of your simulation and all files with analysis of your simulation will have the header. Experience of running many simulations shows that one never has enough information describing details of a simulation done some time ago to identify that simulation later. Use the header to identify your run.
  • Step in the expansion parameter da . This defines how many integration steps the code will do untill it runs to the redshift zero. If you would like to make N steps and you start at redshift z , da = (1 - ${1\over 1+z}$)/N . The step da should be (significantly) smaller than the initial expansion parameter a_init = - ${1\over 1+z}$ .
  • Seed for random numbers. Use any integer number in the range 1 - (2³¹ - 1) (2³¹ $\approx$ 2.1478 x 10⁹) .

Next you will run PMstartCDM which is the program that actually generates initial conditions for the PM code. It will generate two files, which PMmain reads and updates: PMcrd.DAT (information on the cosmological model and parameters of the run) and PMcrs0.DAT (coordinates and velocities of particles). If you run a CHDM simulation, you will have more data files with data for hot neutrinos. PMstartCDM will ask you to provide some parameters. If you created file InStart.dat using the program PMmodels, simply provide the file as input: PMstartCDM < InStart.dat .