| 11:07:56 AM PDT - Fri, May 22nd 2015 |
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I think that those coupled cluster methods you are interested in will require a lot of RAM. Have you managed to get them working with disk based IO schemes? I couldn't, and I was told that the disk based IO schemes should be considered unsupported: http://nwchemgit.github.io/Special_AWCforum/st/id1360/Floating_Point_Exception_usi...
If you are going to frequently run coupled cluster jobs, I would skip spending money on fast disks for each node and shift the money to RAM. For TDDFT I don't know.
I would guess that NWChem file access patterns are largely sequential for big files, but there is no need to guess. You can run a trial job under strace and look at the file access calls to see the access patterns.
If you are an academic you should also get Intel's compilers and MKL and use them to build NWChem. It's free for academics and will give you a modest performance boost over using GNU tools. That should help you get the most performance per dollar out of your hardware budget.
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