PHANTOM is a public SPH code that can be coupled to CMacIonize to perform RHD simulations. This setup uses the CMacIonize Fortran library. At specific times during the SPH calculation, the particle positions, masses and smoothing lengths are passed on to the library. CMacIonize then constructs a Voronoi grid using the particle positions as Voronoi cell generators and maps the particle densities onto this grid. This grid is then used for a photoionization simulation. At the end of the simulation, the resulting hydrogen neutral fractions are returned to PHANTOM and used to update the thermal properties of the SPH particles.

While this sounds all very good, there are a few technical challenges when setting up these simulations, ranging from installing both PHANTOM and CMacIonize, over making sure both codes can talk to each other, to choosing good values for the many parameters that control the hybrid code. This tutorial aims to address these issues.

Installation

Obtaining and installing PHANTOM

A very comprehensive manual on getting started with PHANTOM can be found on https://bitbucket.org/danielprice/phantom/wiki/getstarted. Below are some known pitfalls:

When checking out the latest version of the code from the BitBucket repository, make sure to check that you have a stable version (this can be verified from the git tag using git describe). The safest way to do this is by using the stable branch of the repository (git checkout stable).
Make sure to set the correct environment variables before invoking any make command or running phantom: the OMP_SCHEDULE and OMP_STACKSIZE variables described at the start of the manual and the SYSTEM variable that specifies the Fortran compiler to use.
It is good practice to keep the PHANTOM source directory clean; put your simulation files in another directory (e.g. phantom-build).

Obtaining and installing CMacIonize

This is already covered in another tutorial. Note that the main development of the coupling module is done in a fork of the main repository. So it might be worthwhile to use that version of the code. Since a fork acts as a completely independent repository, this means you will need to clone it into a separate folder outside the main CMacIonize folder.

Telling PHANTOM where to find CMacIonize

More information here.

Running a PHANTOM+CMacIonize RHD simulation