<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:'times new roman', 'new york', times, serif;font-size:12pt"><div>Yes, ideally I didn't want to, but I read somewhere on mailing list that one shouldn't use define = -DFLEXIBLE while running dynamics. So I thought I will use restrained water...</div><div><br></div><div>I'll move back to -DFLEXIBLE though, if I got a successful mdrun for restrained water.</div><div><br></div><div>Thanks,</div><div>Majid</div><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><br><div style="font-family:arial, helvetica, sans-serif;font-size:10pt"><font size="2" face="Tahoma"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Justin A. Lemkul <jalemkul@vt.edu><br><b><span style="font-weight: bold;">To:</span></b> Discussion list for GROMACS users <gmx-users@gromacs.org><br><b><span style="font-weight:
bold;">Sent:</span></b> Fri, April 22, 2011 10:44:45 AM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [gmx-users] DNA not wrapping around CNT in MD simulation<br></font><br>
<br><br>majid hasan wrote:<br>> I just checked and DNA position should not be restrained because I didn't use define = -DPOSRES in .mdp file. I am going to run it for a longer time now, and use position restraints for water<br>> <br><br>What purpose does restraining the water have? You'll be trying to observe diffusion of your DNA or CNT through an immobile solvent.<br><br>-Justin<br><br>> Thank You,<br>> Majid.<br>> <br>> ------------------------------------------------------------------------<br>> *From:* Mark Abraham <<a ymailto="mailto:Mark.Abraham@anu.edu.au" href="mailto:Mark.Abraham@anu.edu.au">Mark.Abraham@anu.edu.au</a>><br>> *To:* Discussion list for GROMACS users <<a ymailto="mailto:gmx-users@gromacs.org" href="mailto:gmx-users@gromacs.org">gmx-users@gromacs.org</a>><br>> *Sent:* Fri, April 22, 2011 1:51:47 AM<br>> *Subject:* Re: [gmx-users] DNA not wrapping around CNT in MD simulation<br>>
<br>> On 4/22/2011 6:48 PM, Mark Abraham wrote:<br>>> On 4/22/2011 4:54 PM, majid hasan wrote:<br>>>> Dear All,<br>>>> <br>>>> I am doing a MD simulation of dna, and cnt in water. I get a stable simulation in which DNA, and CNT wiggles around there positions, but they don't seem to be attracted towards each other. CNT starts in the middle of the box and just moves a little, and DNA starts at top right corner of the box and remains there throughout the simulation.<br>>>> <br>>>> movie of .trr file is here:<br>>>> <br><span>>>> <a target="_blank" href="http://phas.ubc.ca/%7Emajid/Project/cntdna.mpg">http://phas.ubc.ca/%7Emajid/Project/cntdna.mpg</a></span><br>>>> <br>>>> My .mdp files are placed here (both .mdp files are same except for the value of integrator):<br><span>>>> <a target="_blank"
href="http://phas.ubc.ca/%7Emajid/Project/lbfgs.mdp">http://phas.ubc.ca/%7Emajid/Project/lbfgs.mdp</a> (used for EM)</span><br><span>>>> <a target="_blank" href="http://phas.ubc.ca/%7Emajid/Project/md.mdp">http://phas.ubc.ca/%7Emajid/Project/md.mdp</a> (used for MD)</span><br>>>> <br>>>> <br>>>> <br>>>> I created cnt, and dna using following commands:<br>>>> For dna: pdb2gmx -f dna.pdb -o dna.gro -p dna.top -ff select (Selected amber99sb, and TIP3P water model)<br>>>> For cnt: g_x2top -f cnt.gro -o cnt.top -ff select -pbc (selected amber99sb)<br>>>> For mixing and solvation: genbox -cp cnt.gro -ci dna.gro -o cntdna.gro -nmol 1 -try 20 genbox -cp cntdna.gro -cs spc.gro -o cntdnasol.gro <br>>>> In the dna.top file, amber99sb/ions.itp, and a position restraint file was also included along with tip3p.itp. I mentioned it because I am not sure why would
it add ions and position restraints on adding water?<br>>> <br>>> #including molecule .itp files adds nothing to the system - only the potential to have molecule type(s). The system is defined in the [system] directive, and must match the corresponding coordinate file.<br>>> <br>>>> It seems that something is wrong with non-bonded interactions, but I don't understand what?<br>>> <br>>> Why aren't you following a proper equilibration protocol before trying to make observations? You might be using position restraints, have your species too far apart, or simply have not simulated long enough to observe any movement. 200ps is an eye-blink.<br>> <br>> Actually, you simulated 20ps. Your MD timestep is 0.2fs, which is unreasonably short. 100,000 of them is far too short to see anything happen.<br>> <br>> Mark<br>> <br><br>-- ========================================<br><br>Justin A. Lemkul<br>Ph.D.
Candidate<br>ICTAS Doctoral Scholar<br>MILES-IGERT Trainee<br>Department of Biochemistry<br>Virginia Tech<br>Blacksburg, VA<br>jalemkul[at]<a target="_blank" href="http://vt.edu">vt.edu</a> | (540) 231-9080<br><span><a target="_blank" href="http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin">http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin</a></span><br><br>========================================<br>-- gmx-users mailing list <a ymailto="mailto:gmx-users@gromacs.org" href="mailto:gmx-users@gromacs.org">gmx-users@gromacs.org</a><br><span><a target="_blank" href="http://lists.gromacs.org/mailman/listinfo/gmx-users">http://lists.gromacs.org/mailman/listinfo/gmx-users</a></span><br><span>Please search the archive at <a target="_blank" href="http://www.gromacs.org/Support/Mailing_Lists/Search">http://www.gromacs.org/Support/Mailing_Lists/Search</a> before posting!</span><br>Please don't post (un)subscribe requests to the list. Use
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