Hello all, I am trying to test the martini force field with PME for a charged system that contains na+, water, surfactant, octane molecules at 298K and P=0.1MPa. My system works well, if i use the standard shift parameters (correct temp, and pressure). But for for the simulation with PME , the temp of the system decrease to 290 K. Below my *.mdp parameters for a NPT equil at 298K
integrator = md dt = 0.020 nsteps = 10000 ; 200ps nstcomm = 10 comm-grps = ;refcoord_scaling = com nstxout = 0 nstvout = 0 nstfout = 0 nstlog = 1000 nstenergy = 100 ;nstxtcout = 1000 xtc_precision = 100 ;xtc-grps = energygrps = AOT W ION OCT nstlist = 10 ns_type = grid pbc = xyz rlist = 1. ; PME parameters coulombtype = PME rcoulomb = 1.2 rvdw = 1.2 fourierspacing = 0.12 fourier_nx = 0 fourier_ny = 0 fourier_nz = 0 pme_order = 4 tcoupl = v-rescale tc-grps = AOT_W_ION OCT tau_t = 1.0 1.0 ref_t = 298 298 Pcoupl = berendsen Pcoupltype = isotropic tau_p = 1.0 compressibility = 4.5e-5 ref_p = 1.0 ;gen_vel = no ;gen_temp = 0 ;gen_seed = 473529 ; MARTINI and CONSTRAINTS ; for ring systems and stiff bonds constraints are defined ; which are best handled using Lincs. constraints = none constraint_algorithm = Lincs unconstrained_start = no lincs_order = 4 lincs_warnangle = 3 Results obtained with W/ PME Statistics over 10001 steps using 1001 frames Energies (kJ/mol) Bond G96Angle LJ (SR) Coulomb (SR) Coul. recip. 1.63789e+04 1.25195e+03 -4.02093e+05 -8.22079e+03 -4.86843e+04 Potential Kinetic En. Total Energy Temperature Pressure (bar) -4.41367e+05 7.81801e+04 -3.63187e+05 2.90373e+02 -1.76470e+01 T-AOT_W_ION T-OCT 2.90629e+02 2.90357e+02 Results W:o PME Energies (kJ/mol) Bond G96Angle LJ (SR) Coulomb (SR) Potential 1.60482e+04 1.24820e+03 -3.34608e+05 -7.33665e+02 -3.18046e+05 Kinetic En. Total Energy Temperature Pressure (bar) 8.02685e+04 -2.37777e+05 2.98129e+02 -3.07123e+01 Box-X Box-Y Box-Z 1.52926e+01 1.52926e+01 1.52926e+01 T-AOT_W_ION T-OCT 2.98141e+02 2.98129e+02 Did I miss something ? Note that for the moment i do not use the polarizable water model. Thanks for your help Stephane -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists