ERIS is a program for calculation of distributions of electron/nuclear densities and Patterson functions from observed structure factors by means of the maximum entropy method (MEM). It is a successor of MEM calculation programs Dysnomia, PRIMA, and ALBA. ERIS is a part of the VENUS software package.

ERIS is distributed free of charge but currently copyrighted with its source code not open to the public because we wish to control its development and future by ourselves. Permission to use this software is hereby granted under the following conditions:

1. Whenever original results acquired with ERIS are published in journals, proceedings, and review articles, the program name "ERIS" should explicitly be stated. A paper about ERIS, describing its original features, is currently under preparation. Once it is published, it should be cited.
2. ERIS is provided "as is" without any expressed or implied warranty. We do not provide any technical support for free.
3. You should not redistribute any copy of the distributed files unless you have a written permission from us.

If you find a problem or a bug on use of ERIS, please let us know and help us improve it.

• ERIS.zip (ver. 0.99, built on Jul. 24 2024, 24.0MB)
  For 64-bit version of Windows.

• ERIS.dmg (ver. 0.99, built on Jul. 23 2024, 11.9MB)
  This is a universal binary version that runs on both Intel CPUs and Apple Silicon. It requires macOS 10.10 or newer on Intel CPUs and macOS 11 or newer on Apple Silicon.

• ERIS-x86_64.tar.bz2 (ver. 0.99, built on Jul. 23 2024, 3.20MB)
• ERIS-arm64.tar.bz2 (ver. 0.99, built on Jul. 23 2024, 2.53MB)

• ERIS_Examples.zip (3.87MB, Uploaded on Jul. 14 2024)

• ERIS_Manual.pdf (122KB, uploaded on Dec. 2 2014)

• K. Momma, T. Ikeda, A. A. Belik and F. Izumi: Dysnomia, a computer program for maximum-entropy method (MEM) analysis and its performance in the MEM-based pattern fitting. Powder Diffr., 28, 184-193, (2013).
• K. Momma and F. Izumi: Evaluation of algorithms and weighting methods for MEM analysis from powder diffraction data, Z. Kristallogr. Proc., 1, 195-200 (2011).
• F. Izumi & K. Momma: Three-dimensional visualization of electron- and nuclear-density distributions in inorganic materials by MEM-based technology. IOP Conf. Ser.: Mater. Sci. Eng., 18, 022001 (2011).

• Jul. 24 2024 ver. 0.99
  
  • Implemented the maximum entropy Patterson method.
  • Implemented a feature to automatically determine the best weighting parameters.