Author Topic: Grids and Memory Usage  (Read 336 times)

patrickmelix

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Grids and Memory Usage
« on: October 09, 2020, 09:58:40 AM »
Dear RASPA-Devs,

In contrast to the vdW parameter assignment, the vdW grids seem not to support pattern matching of atom names. At least when I try to create a grid with a pattern instead of the full atom name, the code complains.

It seems that one can symlink a created grid file to prevent storing the same grid multiple times, but upon execution of the code, the memory consumption remains unaffected (as is to be expected).

Is it somehow possible to make the code use the same grid for several atom types in order to reduce the memory footprint of the job? Or is there another way to achieve this, that I am missing (adsorbate definition, ...)? In bigger molecules with varying atomic charges but equal vdW parameters, this is quite a bottleneck for me at the moment.

My C is really rusty, so I was not able to understand enough of the code to check myself or even implement a new feature, sorry...

Thanks for your support!
Best Regards,
Patrick

David Dubbeldam

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Re: Grids and Memory Usage
« Reply #1 on: October 20, 2020, 05:56:23 PM »
For each sigma of an adsorbate-atom it needs to create a different grid. You can list with atoms-types you would like to create grids for.
There is only a single extra grid needed for electrostatics.

patrickmelix

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Re: Grids and Memory Usage
« Reply #2 on: October 23, 2020, 05:35:45 PM »
Dear David,

thanks for your answer. I guess my main question was not clear enough: Is it possible to make the code use the same vdW grid for two differently named atoms that have the same sigma value?

An example situation would be: Two atoms c_a and c_b, same vdW but different charges.

When creating the grid, I see that the two grid files for c_a and c_b are exactly the same (same md5sum of the vdW gridfile). When running GCMC simualtions, these two grid files are both loaded to the RAM. Ideally, I would like to tell RASPA2 to use the same grid for both atoms. This would halve the RAM requirements for that example job.

Hope this makes my question a bit more clear.
Thanks for your help!
Best Regards,
Patrick