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LEEDpat4
(LEED pattern analyzer)

Version 4.2 (December 2015)


PC-based software tool to visualize and analyze LEED patterns of substrates and overlayers


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PROGRAM CAPABILITIES

LEEDpat is designed to help interpret experimentally observed LEED spot patterns for well-ordered surfaces especially in the presence of superlattices. In particular, LEEDpat allows one to tell which 2D surface lattices are compatible with an observed LEED pattern. Rotational domains and glide plane extinction of spots are taken into account (the latter at normal incidence only). For further details see LEEDpat manual.

LEEDpat also provides extensive 2D symmetry information, showing all rotational, mirror and glide symmetries that are compatible with the observed pattern. This allows the user to narrow down possible structural models of the surface and to propose atomic positions in the actual structure. However, LEEDpat does not itself predict structural models or atomic coordinates: it does not calculate spot intensities, which would be needed to determine atomic positions.

The user can select any basic 2D substrate lattice (square, hexagonal, rectangular, or oblique), including any possible symmetries (i.e. any of the 17 two-dimensional space groups). The user can also specify any commensurate or incommensurate superlattice, again with any possible symmetries (commensurate only). LEEDpat then draws both a real-space lattice and a LEED pattern (representing reciprocal lattices), including the option of symmetry-related domain orientations (of equal weight). The user can thus, by trial and error, find the pattern that best matches the experiment.

Version 4 of LEEDpat includes many improvements and new features. In particular, it offers now The present version 4.2 of LEEDpat has some general limitations (which cannot be overcome) and simplifications (which may be fixed in later versions): Despite these limitations, LEEDpat can simulate a large fraction of observed patterns, and thus should be useful in most cases.

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SOFTWARE RUNS ON THE FOLLOWING HARDWARE:

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DOWNLOADING

Latest update version as of January 13, 2016

Start downloading the LEEDpat package in a single file (3 MB) by identifying yourself with your name and email address.
(This information will be used ONLY for announcements of major updates and not passed on to others. Obviously fake or obscene addresses will not be accepted.)

Your name

Your e-mail address

To complete downloading click the download button.

     

After having downloaded file LEEDpat42Install.exe you may install LEEDpat on your PC. For instructions see INSTALLATION on this page. You may return to this page from the download page by clicking the "RETURN TO LEEDpat homepage" button in the download page.

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INSTALLATION AND RUNNING:

The INSTALLATION of LEEDpat is straightforward. It requires that you have Administrator status on your PC and and consists in the most general case of four steps. (Note that your browser may have download switches set such that one or more of the following steps are performed automatically.)
  1. Unpack all files by running the downloaded file LEEDpat42Install.exe. (Your browser may use a default directory for file downloading. Then you may have to look for this file in your PC with Window's find option.) This will ask you for the name of an installation subdirectory, e.g. c:\TEMP (or any other temporary directory, which must be different from the permanent directory where you wish LEEDpat to be installed). This subdirectory will contain all system installation files and possibly a file Readme.1st which describes latest changes and gives further advice concerning the installation. Note that the installation directory cannot be used as the final LEEDpat directory, see step 2.

  2. Install all LEEDpat files by running Setup.exe inside the installation subdirectory, see step 1. This will ask you for the name of the final LEEDpat subdirectory, e.g. "c:\Program files (x86)\LEEDpat42" (or any other permanent directory, called $LEEDpatexec below), to contain the LEEDpat executable package.

  3. Set a LEEDpat icon on the desktop using e.g. the MS Windows Explorer (create a shortcut of LEEDpat42.exe in directory $LPexec and move it to the desktop.)

  4. Clean up by removing all files from the installation directory TEMP. You may leave the original download file LEEDpat42Install.exe for backup purposes.
NOTE that when unpacking the installation package with MS Windows 10, depending on the security settings, you may get an opening screen "Windows protected your PC" suggesting to abort the installation with a bold text "Don't run" at the bottom. You can ignore this warning by clicking at the "More info" text which shows another bold text "Run anyway" at the bottom. Clicking this button allows you to proceed with the installation. Microsoft considers any software not registered with Microsoft and not available in the Microsoft Store as "unrecognized" and and risky to run.

NOTE that the installation package includes Windows system components where some may be versions older than those in your present Windows installation. Always keep your latest component version, i.e. in each case when prompted, DO NOT replace your existing system components by older versions of the Balsac installation package.

NOTE that Microsoft may not include the Visual Basic 6 runtime environment (required by LEEDpat) in your Windows installation, versions 8 and later, by default. However, the VB6 runtime environment can be downloaded from Microsoft and installed in your Windows PC free of charge.

You can inspect the LEEDpat users manual in directory $LEEDpatexec but also while running LEEDpat (using the Help menu entry).

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HOW TO CONTACT THE AUTHORS

We are open to any questions and suggestions concerning the LEEDpat software. You can contact the authors using addresses

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