NWChem problems when using more than one core

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loening
Posts: 5
Joined: Fri Aug 07, 2020 1:27 am
Full Name: Nikolaus Loening
Organization: Lewis & Clark College
Subdiscipline: Chemistry

NWChem problems when using more than one core

Post by loening »

I'm posting this here as there isn't a WebMO 24 forum. In trying to setup NWChem 7.2.2 with WebMO 24, it appears that it will only run successfully if the number of cores is limited to 1. If you set up the calculation with more than 1 core, the job fails with the output "Cannot execute /usr/bin/nwchem: No such file or directory". This problem was also present with WebMO 20 when using NWChem 7.0.2. I imagine it has something to do with the fact that the command to initiate NWChem needs to be different when more than one core is used (as it needs to be run via mpirun)...

So, for the moment, I've got to setup the WebMO interface to limit the number of cores to 1, but it'd be nice to be able to run things in parallel at some point in the future.
schmidt
Posts: 96
Joined: Sat May 30, 2020 3:00 pm
Full Name: JR Schmidt
Organization: WebMO, LLC

Re: NWChem problems when using more than one core

Post by schmidt »

This requires just a bit of tweaking, currently, since (as you point out) NWChem is run differently for serial vs. parallel.

In run_nwchem.cgi, you should edit the line under:

# This exec statement may need to be changed if you are not using MPI

In particular, you likely need to provide the full path to 'mpirun' or equivalent for your system. This should resolve the issue.
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