[gmx-developers] Cubic splines - again
David van der Spoel
spoel at xray.bmc.uu.se
Mon Aug 21 14:40:43 CEST 2006
Mathias PUETZ wrote:
> I also have a question about the cubic spline formula used for
> potentials and forces:
> As I understand it the spline formula employed by GROMACS enforces that
> potentials and their second derivates are continuous at the tables sites,
> but the first derivates, hence the forces computed from the tables, are
> There is always a small discontinuity at the table sites for the first
> derivatives and therefore the forces.
> I stumbled a across this when I used Eric's kernel tester for BlueGene
> I guess my question is: Do you really want a spline formula that makes
> the forces discontinous ?
> Wouldn't it actually make more sense to use a spline formulat that
> forces the potential and
> its first derivate to be continuous ? What's the rationale behind making
> the second derivate
> continuous anyway ?
what makes you think the forces are not continuous?
> Viele Grüsse / Best regards,
> Dr. Mathias Pütz
> IT Specialist for Application Perfomance
> Deep Computing - Strategic Growth BusinessDeep
> IBM Systems & Technology Group
> e-mail: mpuetz at de.ibm.com
> mobile: + 49-(0)160-7120602
> fax: + 49-(0)6131-84-6660
> IBM Deutschland GmbH
> Department B458
> Hechtsheimer Str. 2 / Building 12
> 55131 Mainz
> gmx-developers mailing list
> gmx-developers at gromacs.org
> Please don't post (un)subscribe requests to the list. Use the
> www interface or send it to gmx-developers-request at gromacs.org.
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://folding.bmc.uu.se
More information about the gromacs.org_gmx-developers