Hi Gromacians<br><br>I want to do equilibration of water (spc
model) first in the NVT ensemble and then in the NPT ensemble to
maintain a temperature of 300K and a pressure of 1 bar respectively. The
NVT equilibration works fine and the average temperature turns out to
be 299.229 K.<br>
<br>Energy Average RMSD Fluct. Drift Tot-Drift<br>------------------------------<div id=":72">-------------------------------------------------<br>Temperature 299.229 10.3092 10.2463 0.0393873 3.93877<br>
Heat Capacity Cv: 12.494 J/mol K (factor = 0.00118698)<br><br> when
i do NPT equilibration i am not getting the desired pressure as 1 bar
or atleast close to 1 bar (between 1-1.4 bar). In the mdp file i used semiisotropic
pressure coupling type because i want to fix the length of the box same
on two axis as that of the original box size and want to change it only
on one axis. can any one tell me why iam not getting the desired pressure
of 1 bar?. <br>
<br>Energy Average RMSD Fluct. Drift Tot-Drift<br>-------------------------------------------------------------------------------<br>Pressure (bar) 7.4339 574.052 573.574 0.812129 81.2138<br>
<br>Given below is my mdp file (NPT equilibration). any help is highly appreciated.<br><br>title = DCE NVT equilibration <br>cpp = usr/bin/cpp <br>integrator = md <br>nsteps = 100000<br>
dt = 0.001 <br>nstxout = 100 <br>nstvout = 100 <br>nstenergy = 100 <br>nstlog = 100 <br>ns_type = grid <br>nstlist = 1 <br>rlist = 1.0 <br>
coulombtype = PME <br>rcoulomb = 1.0 <br>vdwtype = Cut-off <br>rvdw = 1.0 <br>pme_order = 4 <br>fourierspacing = 0.16<br>pbc = xyz <br>
tcoupl = V-rescale <br>tc-grps = system <br>tau_t = 0.1 <br>ref_t = 300 <br>pcoupl = berendsen <br>pcoupltype = semiisotropic <br>
tau_p = 0.5 <br>ref_p = 1.0 1.0 <br>compressibility = 0.0 4.5e-5 <br>DispCorr = Enerpres <br>gen_vel = yes <br>gen_temp = 300 <br>
gen_seed = 173529 <br><br>Regards<br>Vinoth<br>
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