MagneX

MagneX is a massively parallel, 3D micromagnetics solver for modeling magnetic materials. MagneX solves the Landau-Lifshitz-Gilbert (LLG) equations, including exchange, anisotropy, demagnetization, and Dzyaloshinskii-Moriya interaction (DMI) coupling. The algorithm is implemented using Exascale Computing Project software framework, AMReX, which provides effective scalability on manycore and GPU-based supercomputing architectures.

For questions, please reach out to Zhi (Jackie) Yao (jackie_zhiyao@lbl.gov) and Andy Nonaka (ajnonaka@lbl.gov).

Documentation and Getting Help

More extensive documentation is available HERE. Our community is here to help. Please report installation problems or general questions about the code in the github Issues tab above.

Installation

Here are instructions for a basic, pure-MPI (no GPU) installation. More detailed instructions for GPU systems are in the full documentation.

Download AMReX and MagneX Repositories

Make sure that AMReX and MagneX are cloned at the same root location.
>> git clone https://github.com/AMReX-Codes/amrex.git
>> git clone https://github.com/AMReX-Microelectronics/MagneX.git

Dependencies

Beyond a standard Ubuntu22 installation, the Ubuntu packages libfftw3-dev, libfftw3-mpi-dev, and cmake are required.
SUNDIALS is optional and enables Runge-Kutta, implicit, and multirate integrators (more detailed instructions in the full documentation).
heFFTe is a required dependency. At the same level that AMReX and MagneX are cloned, run:
>> git clone https://github.com/icl-utk-edu/heffte.git
>> cd heffte
>> mkdir build
>> cd build
>> cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=17 -DBUILD_SHARED_LIBS=OFF -DCMAKE_INSTALL_PREFIX=. -DHeffte_ENABLE_FFTW=ON -DHeffte_ENABLE_CUDA=OFF ..
>> make -j4
>> make install

Build

GNU Make (Primary)

Navigate to MagneX/Exec/ and run:
>> make -j4

CMake (Alternative)

MagneX also supports building with CMake, which can automatically download and build dependencies.

Basic CMake Build

# CPU build with default options (NOACC backend)
cmake -S . -B build
cmake --build build -j 4

# OpenMP build  
cmake -S . -B build -DMagneX_COMPUTE=OMP
cmake --build build -j 4

# CUDA build
cmake -S . -B build -DMagneX_COMPUTE=CUDA
cmake --build build -j 4

Core Configuration Options

• MagneX_COMPUTE: NOACC (default), OMP, CUDA, HIP - Computing backend
• MagneX_MPI: ON (default), OFF - Multi-node support
• MagneX_FFT: ON (default), OFF - FFT support
• MagneX_SUNDIALS: OFF (default), ON - SUNDIALS ODE solver support

External Dependencies

AMReX Configuration:

# Use external AMReX installation
cmake -S . -B build \
  -DMagneX_amrex_internal=OFF \
  -DAMReX_DIR=/path/to/amrex/lib/cmake/AMReX

# Use local AMReX source directory
cmake -S . -B build -DMagneX_amrex_src=/path/to/amrex/source

# Use custom AMReX repository/branch
cmake -S . -B build \
  -DMagneX_amrex_repo=https://github.com/user/amrex.git \
  -DMagneX_amrex_branch=my_branch

# Test with specific AMReX pull request (CI/testing)
cmake -S . -B build -DMagneX_amrex_pr=1234

SUNDIALS Configuration (when MagneX_SUNDIALS=ON):

# Use external SUNDIALS installation
cmake -S . -B build \
  -DMagneX_SUNDIALS=ON \
  -DMagneX_sundials_internal=OFF \
  -DSUNDIALS_DIR=/path/to/sundials/lib/cmake/sundials

# Use local SUNDIALS source directory
cmake -S . -B build \
  -DMagneX_SUNDIALS=ON \
  -DMagneX_sundials_src=/path/to/sundials/source

Example Build Commands

# Build with local AMReX source (recommended for development)
cmake -S . -B build -DMagneX_amrex_src=../amrex
cmake --build build -j 4

# OpenMP build with SUNDIALS support
cmake -S . -B build \
  -DMagneX_COMPUTE=OMP \
  -DMagneX_SUNDIALS=ON
cmake --build build -j 4

# CUDA build with external AMReX
export CMAKE_PREFIX_PATH=/path/to/amrex/install:$CMAKE_PREFIX_PATH
cmake -S . -B build \
  -DMagneX_COMPUTE=CUDA \
  -DMagneX_amrex_internal=OFF
cmake --build build -j 4

Running MagneX

GNU Make builds (from Exec directory)

You can run the following to simulate muMAG Standard Problem 4 dynamics:
>> ./main3d.gnu.MPI.ex standard_problem_inputs/inputs_std4

CMake builds (from project root directory)

# For CPU build (NOACC backend)
./build/main3d.gnu.MPI.ex Exec/standard_problem_inputs/inputs_std4

# For OpenMP build
./build/main3d.gnu.MPI.OMP.ex Exec/standard_problem_inputs/inputs_std4

# For CUDA build  
./build/main3d.gnu.MPI.CUDA.ex Exec/standard_problem_inputs/inputs_std4

# Using the convenience symlink
./build/magnex Exec/standard_problem_inputs/inputs_std4

Visualization and Data Analysis

Refer to the following link for several visualization tools that can be used for AMReX plotfiles.

Visualization

Data Analysis in Python using yt

You can extract the data in numpy array format using yt (you can refer to this for installation and usage of yt. After you have installed yt, you can do something as follows, for example, to get variable 'Mx' (x-component of magnetization)

import yt
ds = yt.load('./plt00010000/') # for data at time step 10000
ad0 = ds.covering_grid(level=0, left_edge=ds.domain_left_edge, dims=ds.domain_dimensions)
Mx_array = ad0['Mx'].to_ndarray()

Publications

1. Z. Yao, P. Kumar, J. C. LePelch, and A. Nonaka, MagneX: An Exascale-Enabled Micromagnetics Solver for Spintronic Systems, in preparation.