* Mark Abraham <[email protected]> [2009-06-17 15:31:43 +1000]:
Florian Dommert wrote:* Mark Abraham <[email protected]> [2009-06-17 14:14:22 +1000]:Florian Dommert wrote:However I am very confident and in case of success, that there will besoon an error estimate for the Ewald Sum available, which will be the first step to the an implementation a tuning routine for the SPME paramters to achieve optimalbalance between performance and accuracy ;)I've already implemented a version of mdrun that actually computes the RMS error in the force components under PME, and am planning to release it soon.That is very nice to hear, how do you compute the error ? By comparing to anEwald Sum ?Holding beta fixed, I compare force components with those from a converged real-space summation and high Fourier grid density & interpolation order.
So you have to perform a very costly simulation for every system, when you gather the reference force ? And which beta do you choose, because if you take the right choice you can decrease the computational cost extremely. So theoretically at first you have to find the right beta by sampling through the corresponding parameter space with a fixed Interpolation order and grid size. In the optimal range a change of beta within 0.1 will yield a difference in the error of about 10-1 this trend continues around +/- 0.5 of the optimal value for beta. Flo
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-- Florian Dommert Dipl.-Phys. Institute for Computational Physics University Stuttgart Pfaffenwaldring 27 70569 Stuttgart Tel: +49 - 711 / 6856-3613 Fax: +49 - 711 / 6856-3658 EMail: [email protected] Home: http://www.icp.uni-stuttgart.de/~icp/Florian_Dommert !! PGP-ENCODED emails preferred !!
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