LEA: program to compute nucleon-nucleus scattering or nucleon knockout by electron scattering

James J. Kelly
Department of Physics
University of Maryland
College Park, MD 20742 USA

LEA is a versatile program for studying nucleon-nucleus scattering or nucleon-knockout by electron scattering. The name is an acronym for Linear Expansion Analysis which is based upon its original application to fitting either effective interactions or transition densities to nucleon-nucleus scattering data using models represented by linear expansions; we retain the name even though many other applications are now possible.



Regrettably, documentation has not kept pace with development. The most recent documentation of the program is a user manual that describes the May 1995 version. Although there have been minor changes to the input since then, most nucleon-nucleus options are documented quite thoroughly. Several papers have been published describing the formalism, but no documentation exists for use of the nucleon knockout options. Fortunately, most routines contain extensive comments which should permit input to be constructed by reading source code and modifying samples. I hope to bring the user manual up to date eventually.

Click here to obtain manual for May 1995 version.


The source files are written in nearly standard Fortran, except for the use of generic function names, and will compile under both Fortran 77 or Fortran 90.  LEA has been run successfully on DEC platforms under both VMS and UNIX, SUN under UNIX, IBM under AIX, among others.  However, DEC and AIX versions are no longer supported explicitly.  The present version compiles under g77 and should run on any linux or standard unix platform without modification.  LEA uses a library called  JJKLIB that contains a large collection of Fortran routines used by many of my programs. You may obtain JJKLIB from the website indicated below.

Recent versions

Version 7.6 includes fully relativistic model for nucleon electromagnetic knockout.

Installation instructions (UNIX)

  1. Extract the files

    The source files are provided in the form of a self-extracting archive file. The files were archived using tar, compressed with gzip, and encoded using uuencode. On unix systems, the following steps

    1. download lea.uu
    2. strip any mailer junk
    3. chmod 744 lea.uu
    4. lea.uu

    will produce a set of source files in the current directory and will create several subdirectories.  Choose the top directory carefully and assign it to the environment variable lea.

  2. Produce JJKLIB

    Obtain and make jjklib, if not already available.

  3. Make LEA

    The script make_all should compile the libraries and then link lea.exe using gmake.

  4. Install interaction files

    Obtain data files for nucleon-nucleon effective interactions from the web site listed above.  Create an environment variable forces identifying this directory. 

  5. Check sample calculations

    A set of sample calculations is provided in the SAMPLES subdirectory. You will probably need to modify the scripts to contain the correct pathnames for the image and for data files, such as interactions. It may also be wise to save a copy of the sample input and output somewhere else for comparison with your results before running any test cases that would overwrite the output. The script redo in the SAMPLES subdirectory should run all the test cases provided.  Once your installation successfully reproduces the sample calculations, you will be ready to proceed.


This material is distributed free of charge for research purposes and carries no express or implied warranties. You may install these routines and may make whatever modifications are required for any noncommercial application, provided that proper acknowledgment is given in custom versions and in publications, but support will be provided only for approved versions. Please notify me of any errors that are found or extensions that are needed.

Please report errors or problems to: James J. Kelly
Last revised: Oct. 10, 2003