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2.6 Running examples

As a final check that compilation was successful, you may want to run some or all of the examples. You should first of all ensure that you have downloaded and correctly unpacked the package containing examples (since v.4.1 in a separate package):
     tar -zxvf /path/to/package/espresso-X.Y.Z-examples.tar.gz
will unpack several subdirectories into espresso-X.Y.Z/. There are two different types of examples:

Let us first consider the tests. Automated tests for pw.x are in directory tests/. File tests/README contains a list of what is tested. To run tests, follow the directions in the header if file check_pw.x.j, edit variables PARA_PREFIX, PARA_POSTFIX if needed (see below). Same for cp.x, this time in directory cptests/.

Let us now consider examples. A list of examples and of what each example does is contained in examples/README. For details, see the README file in each example's directory. If you find that any relevant feature isn't being tested, please contact us (or even better, write and send us a new example yourself !).

To run the examples, you should follow this procedure:

  1. Go to the examples/ directory and edit the environment_variables file, setting the following variables as needed:
    BIN_DIR: directory where executables reside
    PSEUDO_DIR: directory where pseudopotential files reside
    TMP_DIR: directory to be used as temporary storage area
    The default values of BIN_DIR and PSEUDO_DIR should be fine, unless you have installed things in nonstandard places. TMP_DIR must be a directory where you have read and write access to, with enough available space to host the temporary files produced by the example runs, and possibly offering high I/O performance (i.e., don't use an NFS-mounted directory). NOTA BENE: do not use a directory containing other data, the examples will clean it!
  2. If you have compiled the parallel version of QUANTUM ESPRESSO (this is the default if parallel libraries are detected), you will usually have to specify a driver program (such as mpirun or mpiexec) and the number of processors: see Sec.3.2 for details. In order to do that, edit again the environment_variables file and set the PARA_PREFIX and PARA_POSTFIX variables as needed. Parallel executables will be run by a command like this:
          $PARA_PREFIX pw.x $PARA_POSTFIX < file.in > file.out
    
    For example, if the command line is like this (as for an IBM SP):
          poe pw.x -procs 4 < file.in > file.out
    
    you should set PARA_PREFIX="poe", PARA_POSTFIX="-procs 4". Furthermore, if your machine does not support interactive use, you must run the commands specified below through the batch queuing system installed on that machine. Ask your system administrator for instructions.
  3. To run a single example, go to the corresponding directory (e.g. example/example01) and execute:
          ./run_example
    
    This will create a subdirectory results, containing the input and output files generated by the calculation. Some examples take only a few seconds to run, while others may require several minutes depending on your system. To run all the examples in one go, execute:
          ./run_all_examples
    
    from the examples directory. On a single-processor machine, this typically takes a few hours. The make_clean script cleans the examples tree, by removing all the results subdirectories. However, if additional subdirectories have been created, they aren't deleted.

  4. In each example's directory, the reference/ subdirectory contains verified output files, that you can check your results against. They were generated on a Linux PC using the Intel compiler. On different architectures the precise numbers could be slightly different, in particular if different FFT dimensions are automatically selected. For this reason, a plain diff of your results against the reference data doesn't work, or at least, it requires human inspection of the results.


next up previous contents
Next: 2.7 Installation tricks and Up: 2 Installation Previous: 2.5 Compilation   Contents
Build Daemon user 2012-05-24