GAMESS memory problems

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loening
Posts: 4
Joined: Fri Aug 07, 2020 1:27 am
Full Name: Nikolaus Loening
Organization: Lewis & Clark College
Subdiscipline: Chemistry

GAMESS memory problems

Post by loening »

Not really a major bug, but it would help if the default for the amount of memory for GAMESS calculations was somewhat changed. By default, the amount of memory (specified in the advanced tab) for a job is blank, in which case the calculation defaults to a value of "1" which reserves 1 megaword of memory (2 MB). At least when trying to calculate NMR chemical shifts, this will usually result in an out of memory error:

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 NMR CHEMICAL SHIFT CALCULATION REQUIRES            12656593 WORDS OF MEMORY.
 ***** ERROR: MEMORY REQUEST EXCEEDS AVAILABLE MEMORY
This of course can be fixed by having the user set the amount of memory to something bigger, but I realized that I could make this error a bit less likely to crop up by changing the templates for GAMESS calculations so that if the user doesn't specify the amount of memory to reserve for the job, a larger value (128 megawords, 64 MB) is reserved:

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[%IF memory %] \$SYSTEM MWORDS=$memory \$END\n[% ELSE %] \$SYSTEM MWORDS=128 \$END\n[%END-%]
In these days of computers with multiple gigabytes of RAM, there not reason to be so stingy with the memory allocation! It probably would be more elegant to just add a default value for the amount of memory to use in /public_html/webmo/gamess.html, but I was worried that if I fixed it there it would be overwritten in the next WebMO update.

schmidt
Posts: 34
Joined: Sat May 30, 2020 3:00 pm
Full Name: JR Schmidt
Organization: WebMO, LLC

Re: GAMESS memory problems

Post by schmidt »

In general, I prefer the philosophy of leaving the program default unchanged in the absence of user interaction. HOWEVR in this case the "default" of 1 MW is crazy -- and there does not appear to be a away to override this on a "system" level (e.g. a GAMESS config file). As such, I now specify 128 MW as the default in gamess.html (for next bugfix release)

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