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Hi,<br><br>This is normal.<br>Reaction-field still uses a cut-off, which gives cut-off errors.<br>To make the the error small you will need to reduce tau_t.<br>Or use reaction-field-zero with a buffer region (computationally expensive).<br>The real solution is to simply use PME.<br><br>Berk<br><br>> Date: Wed, 21 Jan 2009 17:51:02 +0100<br>> From: sam.moors@chem.kuleuven.be<br>> To: gmx-users@gromacs.org<br>> Subject: [gmx-users] temperature too high with reaction field<br>> <br>> Hi gmx users,<br>> <br>> I'm trying to simulate a water box filled with TIP3P water.<br>> With PME, everything seems OK.<br>> However, when I switch to reaction field electrostatics,<br>> the temperature in the output files is too high: <br>> 312K instead of 300K (the t_ref value for the whole system).<br>> Maybe there is something wrong with my input paramters?<br>> Below you find my .mdp file<br>> <br>> Thanks,<br>> Sam<br>> <br>> integrator = md<br>> dt = 0.002 ; ps !<br>> nsteps = 20000<br>> nstcomm = 1<br>> nstxout = 500<br>> nstvout = 0<br>> nstlog = 500<br>> nstenergy = 500<br>> nstfout = 0<br>> nstlist = 10<br>> ns_type = grid<br>> rlist = 1.2<br>> coulombtype = Reaction-Field <br>> epsilon_r = 1<br>> epsilon_rf = 78<br>> rcoulomb = 1.2<br>> table-extension = 1<br>> vdwtype = cutoff<br>> rvdw = 1.2<br>> fourierspacing = 0.19<br>> fourier_nx = 0<br>> fourier_ny = 0<br>> fourier_nz = 0<br>> pme_order = 4<br>> ewald_rtol = 1e-5<br>> optimize_fft = yes<br>> ; temperature coupling<br>> Tcoupl = v-rescale<br>> tau_t = 1.0<br>> tcgrps = system<br>> ref_t = 300<br>> ; Pressure coupling<br>> Pcoupl = parrinello-rahman<br>> tau_p = 1.0<br>> compressibility = 4.5e-5<br>> ref_p = 1.0<br>> ; Generate velocites<br>> gen_vel = no<br>> gen_temp = 300<br>> gen_seed = 173529<br>> <br>> <br>> Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm<br>> <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 <br>> www interface or send it to gmx-users-request@gromacs.org.<br>> Can't post? Read http://www.gromacs.org/mailing_lists/users.php<br><br /><hr />What can you do with the new Windows Live? <a href='http://www.microsoft.com/windows/windowslive/default.aspx' target='_new'>Find out</a></body>
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