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Hi,<br><br>The error should not be in the tables, if you are using Gromacs 4.<br>We made sure that the accuracy of the tabulation and interpolation<br>is nearly the full precision (both in single and double precision).<br><br>For these kind of testing purposes you should be using double precision<br>anyhow, which gives you far more accuracy than 10^-4.<br><br>Berk<br><br>> Date: Tue, 6 Jan 2009 14:24:17 +0100<br>> From: dommert@fias.uni-frankfurt.de<br>> To: gmx-users@gromacs.org<br>> Subject: Re: [gmx-users] force evaluation<br>> <br>> * Mark Abraham <Mark.Abraham@anu.edu.au> [2009-01-07 00:13:00 +1100]:<br>> <br>> > Suman Chakrabarty wrote:<br>> >> On Tue, Jan 6, 2009 at 2:29 PM, Florian Dommert<br>> >> <dommert@fias.uni-frankfurt.de> wrote:<br>> >>> Finally it would be very interested in a possiblity to switch off the<br>> >>> vdw interactions easily. So far I used an appropiate topology files with <br>> >>> C6<br>> >>> and<br>> >>> C12 set to zero. Is there an easier solution as using a table filled<br>> >>> with zeros ?<br>> ><br>> > Zeroed tables will be considerably slower than zeroed parameters.<br>> ><br>> > Depending on the way the force field is organized, you might create a <br>> > version of the force field files that zeroes out these parameters. Another <br>> > possibility might be to using the preprocessor mechanism to define the VDW <br>> > parameters only under some circumstances.<br>> <br>> Thank you very much for the help. It seems I went the a good way with<br>> using a preprocessing command to define the zero VDW IA.<br>> <br>> Now I have to find where the difference in the calculation of the<br>> electrostatic forces. Perhaps somebody can tell me, where the forces get<br>> tabulated, that I can take a look at the code there ?<br>> <br>> Cheers,<br>> <br>> Flo<br>> <br>> <br>> ><br>> > Mark<br>> > _______________________________________________<br>> > gmx-users mailing list gmx-users@gromacs.org<br>> > http://www.gromacs.org/mailman/listinfo/gmx-users<br>> > Please search the archive at http://www.gromacs.org/search before posting!<br>> > Please don't post (un)subscribe requests to the list. Use the www interface <br>> > or send it to gmx-users-request@gromacs.org.<br>> > Can't post? Read http://www.gromacs.org/mailing_lists/users.php<br>> <br>> -- <br>> Florian Dommert<br>> Dipl.-Phys.<br>> <br>> Computational and Theoretical Softmatter & Biophysics group<br>> <br>> Frankfurt Institute for Advanced Studies<br>> Johann-Wolfgang-Goethe University<br>> <br>> Ruth-Moufang-Str. 1<br>> 60438 Frankfurt am Main<br>> <br>> Phone: +49(0)69 / 798 - 47529<br>> Fax: +49(0)69 / 798 - 47611<br>> <br>> EMail: dommert@fias.uni-frankfurt.de<br>> Home: http://fias.uni-frankfurt.de/~simbio/Florian_Dommert<br><br /><hr />Express yourself instantly with MSN Messenger! <a href='http://clk.atdmt.com/AVE/go/onm00200471ave/direct/01/' target='_new'>MSN Messenger</a></body>
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