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# 5 Troubleshooting

Almost all problems in QUANTUM ESPRESSO arise from incorrect input data and result in error stops. Error messages should be self-explanatory, but unfortunately this is not always true. If the code issues a warning messages and continues, pay attention to it but do not assume that something is necessarily wrong in your calculation: most warning messages signal harmless problems.

#### 5.0.0.1 Some postprocessing codes complain that they do not find some files

For Linux PC clusters in parallel execution: in at least some versions of MPICH, the current directory is set to the directory where the executable code resides, instead of being set to the directory where the code is executed. This MPICH weirdness may cause unexpected failures in some postprocessing codes that expect a data file in the current directory. Workaround: use symbolic links, or copy the executable to the current directory.

#### 5.0.0.2 error in davcio in postprocessing codes

Most likely you are not reading the correct data files, or you are not following the correct procedure for postprocessing. In parallel execution: if you did not set `wf_collect=.true.`, the number of processors and pools for the phonon run should be the same as for the self-consistent run; all files must be visible to all processors.

Subsections

- - - 5.0.0.1 Some postprocessing codes complain that they do not find some files
    - 5.0.0.2 error in davcio in postprocessing codes

Next: About this document ... Up: User's Guide for the Previous: 4.7 Other tools Contents