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Hi Lin,<div><br></div><div>I would suggest taking a look at the manual, specifically section 6.5 (Removing Fastest Degrees of Freedom), and any general textbook on molecular simulation. Wanting faster results without having an understanding of the method is a good recipe for getting the wrong answer. There are physical and numerical reasons for the parameter choices and it would be good to understand those before proceeding further with molecular dynamics.</div><div><br></div><div>Best of luck,</div><div>Josh</div><div><br></div><div><br></div><div><br><div><div>On May 19, 2009, at 2:27 PM, Chih-Ying Lin wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><br><br>Hi<br>I want to get the simulation results fater and want to set <br><br>the time step<br>dt > = 0.002<br><br><br>what is the upper limit of the time step dt ?<br><br><br>Thank you<br>Lin <br><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">gmx-users mailing list<span class="Apple-converted-space"> </span><a href="mailto:gmx-users@gromacs.org">gmx-users@gromacs.org</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="http://www.gromacs.org/mailman/listinfo/gmx-users">http://www.gromacs.org/mailman/listinfo/gmx-users</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Please search the archive at <a href="http://www.gromacs.org/search">http://www.gromacs.org/search</a> before posting!</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Please don't post (un)subscribe requests to the list. Use the<span class="Apple-converted-space"> </span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">www interface or send it to <a href="mailto:gmx-users-request@gromacs.org">gmx-users-request@gromacs.org</a>.</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Can't post? Read <a href="http://www.gromacs.org/mailing_lists/users.php">http://www.gromacs.org/mailing_lists/users.php</a></div> </blockquote></div><br><div> <span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">------------------------------------------------------------------------------------------------------</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Joshua L. Adelman</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Biophysics Graduate Group Lab: 510.643.2159</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">218 Wellman Hall Fax: 510.642.7428</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">University of California, Berkeley <a href="http://nature.berkeley.edu/~jadelman">http://nature.berkeley.edu/~jadelman</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Berkeley, CA 94720 USA <a href="mailto:jadelman@berkeley.edu">jadelman@berkeley.edu</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">------------------------------------------------------------------------------------------------------</div><br class="Apple-interchange-newline"></span> </div><br></div></body></html>