RT-TDDFT memory usage
Clicked A Few Times
4:51:06 AM PDT - Thu, Oct 29th 2015
I am running a RT-TDDFT calculation on a machine with 64GB memory. I notice memory usage is very low ~1% for each process, but huge scratch files (2-3GB for each process) are created on disk. In order to avoid creating such huge files, i tried to increase memory by specifying

memory total 10000 mb stack 1000 mb heap 1000 mb global 8000 mb noverify


but NWchem's behavior has not changed; it stills makes poor usage of RAM and writes to disk huge scratch files. This is of particular concern, as the disk is SSD with its known limitations. I was thinking of setting up a ramdisk for the scratch files, but is there any better way to prevent writing to disk and use the available memory instead?


Thanks for any suggestion,
Kostas

Clicked A Few Times
6:58:16 AM PDT - Thu, Oct 29th 2015
I have found the solution! Just in case anyone else has the same problem, the solution is very simple: increasing stack memory will prevent writing the AO integrals to disk.

memory total 10000 mb stack 5000 mb heap 1000 mb global 4000 mb noverify


Also, putting

grid nodisk


in DFT section will prevent creation of the (much smaller) grid files.


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