µMAG Evening Session

9th Joint MMM/Intermag Conference
January 7, 2004
Anaheim, CA
Bob McMichael, Session Chair


Welcome and Introduction

Bob McMichael, NIST

magpar, finite element micromagnetics

Werner Scholz, Seagate

OOMMF: Where it is, where is it going?

Don Porter and Mike Donahue, NIST

Open Discussion: Toward a thermal standard problem

Bob McMichael, moderator

Session report:

The MAG evening session ran from 7:30 to approximately 9:30 and drew approximately 90 participants.

Welcome and Introduction

Bob McMichael opened the session with a very brief introduction to muMAG and its objective of fostering improved communication within the micromagnetic community and encouraging improvements in the reliability of micromagnetic computations. The two technical efforts within muMAG are
  1.  Public micromagnetic code
  2.  Standard Problems

magpar, finite element micromagnetics

Werner Scholz then gave a description of the finite element micromagnetic software he developed as a graduate student at the Technical University of Vienna under the guidance of Thomas Schrefl and Josef Fidler. A few weeks before this meeting, Werner had announced the public release of this software via the muMAG mailing list.

The features of magpar include Werner described the open source software packages he incorporated to handle the large matrices and vectors, to perform energy minimization or LLG time integration and ultimately, to make the program run efficiently on parallel processors. The efforts to parallelize the code appear to be quite successful since the computation time scales inversely with the number of processors used.

Official website and distribution site: http://magnet.atp.tuwien.ac.at/scholz/magpar/
The complete source code including documentation and a package of examples are available for download.

Werner requests that all correspondence concerning magpar be directed to the following address only: magpar@magnet.atp.tuwien.ac.at

Werner's presentation ended with a double round of applause and thanks for this very important contribution to the micromagnetic community.

OMMF: Where it is, where is it going?

Don Porter and Mike Donahue reported on the status and future directions for the NIST Object Oriented MicroMagnetic Framework, (OOMMF).

Don described a maintenance release in the 1.1 branch of the OOMMF software, which is centered on the 2D solver mmSolve2D. The new release has basically the same capabilities as the previous release, but includes updates to maintain compatibility with various operating systems and the Tcl/Tk programming language. Support for the Mac operating system (OS X) is included for the first time.

Mike Donahue described an upcoming release in the 1.2 branch of OOMMF. This distribution will include all updates in the new 1.1 release, but it is centered on the 3D solver, Oxsii. The new release incorporates a number of bug fixes and several important new features, including a Runge-Kutta solver for integration of the LLG equations of motion and a problem restart capability.

For users of the 2D mmSolve2D program, Mike described an input file translation utility that translates input files to the format required for 3D Oxsii. Mike presented some examples of the 3D input syntax and showed how to use the Tcl scripting features for flexible input. He also described what is involved in creating an extension module for Oxsii through an example hexagonal anisotropy class.

Mike discussed planned features for the future 1.3 branch of OOMMF, and announced plans to open a contributor website to facilitate user contributions to the code.

Open Discussion: Toward a thermal standard problem

The final item was a discussion geared toward designing a new micromagnetic standard problem to test thermal effects in micromagnetics. As with previous successful standard problems, the new standard problem should have the following properties.
The lively discussion centered primarily around two main issues: whether the Langevin approach, where a fluctuating, random applied field is used to simulate the effects of temperature, is thermodynamicaly rigorous and what kinds of standard problems are best suited as tests for thermodynamic rigor.

A list of suggested problems was generated, and the ideas fell basically into two categories:  steady state problems and thermal switching.
Steady state problems
 Switching problems
Other comments included a suggestion to create a situation where the magnetostatic part of the calculation could be simplified, either by eliminating magnetostatics or by using high anisotropy thin films where the magnetostatics is relatively unimportant and magnetostatic effects can be restricted to short range. The audience was reminded that results should be demonstrated to be independent of discretization.

To wrap up the discussion, it was decided that this report would be written up and disseminated via the µMAG mailing list where the discussion could continue online.

Report submitted by Bob McMichael, Jan 22, 2004.