[gmx-users] Ewald sums too slow?

[David]

On Tue, 2004-06-15 at 19:47, Vincent Ballenegger wrote:
> Hi all,
> For small systems (<100 molecules), I would expect the standard Ewald 
> sum to be faster than the PME method.
> For a system of 64 SPC water molecules in a box of width L=1.2413 nm, I 
> found however that gromacs-3.2.1 is about 85 times slower when using the 
> standard Ewald method instead of PME !!
> Why are the Ewald sums so slow?
stupid implementation. basically we never bothered to do it right other
than for checking PME.
> 
> My input parameters were:
> ewald_rtol               = 1e-05
> fourierspacing = 0.12
> rlist = rcoulomb = rvdw = 0.62 nm
> pme_order                = 6
> epsilon_surface          = 0
> 
> Thanks,
> Vincent
> 
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-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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