Forum Menu

Benchmarks for CCSDTQ

From NWChem

Viewed 84 times, With a total of 1 Posts
Jump to: navigation, search

Just Got Here
Threads 1
Posts 1
I would like to run some high-accuracy calculations on small molecules (two or three atoms) with up to ~10 electrons. I am considering using the CCSDTQ code available in Nwchem (I am not currently a Nwchem user). I am looking for any time/memory benchmarks for the CCSDTQ code; at the moment I am using the MRCC code by M. Kallay but, 1), it is not parallel, 2), in many situations is very, very input/output time-limited and 3), the scaling with basis set size I empirically observe is higher than what it could be in optimal cases (e.g., time scales as N^10 for a 10-electron system, where N is the basis set size for a given molecule).


  • Karol Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
    Send PM
Clicked A Few Times
Threads 0
Posts 8
We don't have the scaling of the CCSDTQ method as a function of the systems size.
However, the scaling of the CCSDT approach was pretty consistent with its N^8 numerical complexity. Of course, the performance of the CCSDTQ implementation may be prone to the choice of the parameters which define the granularity of the code (the so-called "tilesize" parameter). This should be observed especially for the small systems.

When running the CCSDTQ calculations one should rememebr about the local memory requirements defined by the (tilesize)^8. For example, when you define "tilesize 8" in your input, you will need to store 2 object of the tilesize^8 character which is equavalent to 250 GB.


Forum >> NWChem's corner >> General Topics

Who's here now Members 0 Guests 0 Bots/Crawler 1

AWC's: 2.5.10 MediaWiki - Stand Alone Forum Extension
Forum theme style by: AWC