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Hi,<br><br>First, please switch to 4.0.5, I have put several fixes in the pull code<br>in the 4.0 minor releases.<br><br>You did not specify pull_init1, nor pull_start, this means you start pulling <br>at a distance of 0, which means the center of the bilayer.<br>Setting<br>pull_start = yes<br>should fix your problem.<br><br>Berk<br><br><hr id="stopSpelling">Date: Thu, 6 Aug 2009 10:49:26 +0800<br>From: djpittdj@gmail.com<br>To: gmx-users@gromacs.org<br>Subject: [gmx-users] pull code problem<br><br><span class="EC_Apple-style-span" style="font-family: 'times new roman'; font-size: 16px; border-collapse: collapse;">Hi, all:<br>I tried to pull a specific DPPC, say, r3, out of a pre-equilibrated bilayer into the water along the positive z axis. For the pull code parameters, I used:<br>
pull = umbrella<br>pull_geometry = distance<br>pull_vec1 = 0. 0. 1.<br>pull_dim = N N Y<br>pull_nstxout = 1000<br>pull_group0 = bilayer<br>pull_group1 = r3_P<br>
pull_k1 = 500<br>pull_rate1 = 0.001 ;nm/ps<br>integrator = md<br>dt = 0.002 ;ps<br>nsteps = 1000000<br>nstcomm = 1<br>comm_grps = DPP SOL<br>
nstxtcout = 100<br>nstlist = 10 <br>ns_type = grid<br>pbc = xyz<br>rlist = 1.0 <br>coulombtype = PME<br>rcoulomb = 1.0<br>
vdwtype = cut-off<br>rvdw = 1.0<br>ewald_rtol = 1e-5<br>optimize_fft = yes<br>tcoupl = Berendsen<br>tau_t = 0.1 0.1<br>tc_grps = DPP SOL<br>
ref_t = 323 323<br>pcoupl = Berendsen<br>pcoupltype = semiisotropic<br>tau_p = 1.0 1.0 <br>compressibility = 4.5e-5 4.5e-5<br>ref_p = 1.0 1.0 <br>
gen_vel = no<br>gen_temp = 323<br>gen_seed = 173529<br>constraints = all-bonds<br>constraint_algorithm = LINCS<br>lincs_order = 4<br><br>"r3_P" corresponds to an index file that contains the phophorus group of r3, and "bilayer" corresponds to an index file that contains all the lipids except r3.<br>
<br>I'm using GROMACS 4.0.3, but when I looked at the trajectory in VMD, the position of r3 is hardly moved. So what's the right way to pull this specific lipid into the water slab?<br><br>Thanks.<br><br>dj</span><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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