<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">Hello!<DIV><BR class="khtml-block-placeholder"></DIV><DIV>Check out</DIV><DIV><A href="http://wiki.gromacs.org/index.php/Errors#Stepsize_too_small.2C_or_no_change_in_energy._Converged_to_machine_precision.2C_but_not_to_the_requested_precision">http://wiki.gromacs.org/index.php/Errors#Stepsize_too_small.2C_or_no_change_in_energy._Converged_to_machine_precision.2C_but_not_to_the_requested_precision</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Cheers</DIV><DIV>/Per</DIV><DIV><BR><DIV><DIV>17 aug 2007 kl. 18.28 skrev Sheyore Omovie:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"> Dear gmx-users,<BR> <BR> <FONT face="Arial Black, Geneva, Arial, Sans-serif">I have 2 molecules in a box, as usual pdb2gmx saw them as one. i edited the .top file to remove the bonds created between the two molecules, I also added a distance restraint btw the molecules. (The 2 structures have been separately minimized). However, I get the ff message for EM run:</FONT><BR><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">Stepsize too small, or no change in energy.<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">Converged to machine precision,<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">but not to the requested precision Fmax < 1000<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><O:P><FONT face="Times New Roman" color="#000000" size="3"> </FONT></O:P></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">Double precision normally gives you higher accuracy.<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><O:P><FONT face="Times New Roman" color="#000000" size="3"> </FONT></O:P></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">Steepest Descents converged to machine precision in 15 steps,<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">but did not reach the requested Fmax < 1000.<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">Potential Energy<SPAN style="mso-spacerun: yes"> </SPAN>=<SPAN style="mso-spacerun: yes"> </SPAN>1.0246325e+20<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT size="3"><FONT color="#000000"><FONT face="Times New Roman">Maximum force<SPAN style="mso-spacerun: yes"> </SPAN>=<SPAN style="mso-spacerun: yes"> </SPAN>inf on atom 1<O:P></O:P></FONT></FONT></FONT></DIV><DIV style="margin-top: 0in; margin-right: 0in; margin-bottom: 0pt; margin-left: 0in; "><FONT face="Times New Roman" color="#000000" size="3">Norm of force<SPAN style="mso-spacerun: yes"> </SPAN>=<SPAN style="mso-spacerun: yes"> </SPAN>inf</FONT></DIV> I would appreciate any advice on how to fix this.<BR> Rgds<BR> John<BR><BR><HR>See what you’re getting into…before you go there <A href="http://newlivehotmail.com/?ocid=TXT_TAGHM_migration_HM_viral_preview_0507" target="_new">See it!</A><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. 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