Getting Started

Requirements

Microphysics requires

optional dependencies are:

  • CUDA (>= 11)

  • ROCm (>= 6.3.1 — earlier versions have register allocation bugs)

Microphysics is meant to be compiled into an application code as part of its build process, with the network, EOS, integrator, and more picked at compile time. As such, there is not a single library that can be built and linked against.

Below we describe how to use Microphysics in a “standalone” fashion, using the provided unit tests, and as part of an application code.

Standalone

Microphysics can be used in a “standalone” fashion to run the unit tests and explore the behavior of the reaction networks. The main requirement is a copy of AMReX:

git clone https://github.com/AMReX-Codes/amrex.git

We use this for some data structures and the build system. You need to set the AMREX_HOME environment variable to point to the amrex/ directory:

export AMREX_HOME=/path/to/amrex

(where you change /path/to/amrex to your actual path).

A good unit test to start with is burn_cell — this is simply a one-zone burn. In Microphysics/ do:

cd unit_test/burn_cell
make

This will create an executable called main3d.gnu.ex. By default, the test is built with the 13-isotope aprox13 network, helmholtz EOS, and VODE integrator.

Then you can run it as:

./main3d.gnu.ex inputs_aprox13

Here inputs_aprox13 is the inputs file that sets options.

This will output information about the starting and final state to the terminal and produce a file state_over_time.txt that contains the thermodynamic history at different points in time.

Note

See the burn_cell documentation for more details on this unit test and how to visualize the output.

Running with AMReX Application Code

Getting started with Microphysics using either CASTRO or MAESTROeX is straightforward. Because the modules here are already in a format that the AMReX codes understand, you only need to provide to the code calling these routines their location on your system. The code will do the rest.

First we need to define the MICROPHYSICS_HOME environment variable, either at a command line or (if you use the bash shell) through your ~/.bashrc, e.g.:

export MICROPHYSICS_HOME=/path/to/Microphysics

For CASTRO and MAESTROeX the name of the EOS and network are set via the make variables EOS_DIR and NETWORK_DIR. These codes then rely on the Microphysics Make.Microphysics_extern makefile stub (found via the MICROPHYSICS_HOME variable) to add the necessary source to the build. All of the interfaces that these codes use are found in Microphysics/interfaces/.

Other AMReX-based codes can use Microphysics in the same fashion.