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Hi,<br>My system is composed of 900 copies of the same small molecule without charges (atoms a1, a2, a3 + a virtual site). All the atoms a1..a3 interact using a tabulated potential 1 and all the virtual sites of every molecule interact using tabulated potential 2. (The system has two energy groups). This is the reason why I wanted to use two energy groups in the test particle.<br><br>For curiosity, does Gromacs use the Cavity Insertion Widom method?<br><br>Thanks for the advice !<br><br>Harry G.<br><br><hr id="stopSpelling">From: gmx3@hotmail.com<br>To: gmx-users@gromacs.org<br>Subject: RE: [gmx-users] Test Particle Insertion Problem-Gromacs 4.0.3<br>Date: Fri, 15 May 2009 09:18:56 +0200<br><br>
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Hi,<br><br>The issue is slightly different here.<br>Currently TPI in Gromacs is limited to inserting a single charge group.<br>Since energy groups should consist of whole charge groups, the inserted<br>molecule can only consist of a single energy group.<br>You can solve your problem by making the whole inserted molecule an energy group C<br>and then define the proper tables between A-C and B-C.<br><br>I have no clue how your system looks like, but if you have multiple charge groups,<br>won't you molecule be to large for use with TPI?<br>TPI will only work for molecules that are small enough to fit into spontaneously<br>occurring cavities.<br><br>Berk<br><br>> Date: Fri, 15 May 2009 07:50:52 +1000<br>> From: Mark.Abraham@anu.edu.au<br>> To: gmx-users@gromacs.org<br>> Subject: Re: [gmx-users] Test Particle Insertion Problem-Gromacs 4.0.3<br>> <br>> Harry Saavedra wrote:<br>> > Dear All,<br>> > <br>> > I run a test molecule insertion simulation using Gromacs 4.0.3. All the <br>> > molecules of the system work with two energy groups (two tabulated <br>> > potentials), and every atom belongs to a different charge group; but <br>> > Gromacs shows an error message:<br>> > <br>> > > grompp...<br>> > > mdrun ...<br>> > <br>> > Program mdrun, VERSION 4.0.3<br>> > Source code file: force.c, line: 1068 Send <javascript:;><br>> > Fatal error:<br>> > The molecule to insert can not consist of multiple charge groups.<br>> > Make it a single charge group.<br>> > <br>> > <br>> > However,when I set all the atoms of the inserted molecule (A,B,C..) to <br>> > the same charge group (cgnr in the top file), Gromacs displays :<br>> > <br>> > <br>> > >grompp...<br>> > <br>> > Program grompp, VERSION 4.0.3<br>> > Source code file: grompp.c, line: 150<br>> > Fatal error:<br>> > atoms A and B in charge group Z of molecule type 'Protein' are in <br>> > different energy groups<br>> > <br>> > <br>> > There is any way to overcome this problem? How Gromacs can ignore the <br>> > charge groups?<br>> <br>> Energy groups are set in the .mdp file using the groups defined <br>> (implicitly) in the .ndx file. You need a charge group that is a subset <br>> of a single energy group.<br>> <br>> Mark<br>> _______________________________________________<br>> gmx-users mailing list gmx-users@gromacs.org<br>> http://www.gromacs.org/mailman/listinfo/gmx-users<br>> Please search the archive at http://www.gromacs.org/search before posting!<br>> Please don't post (un)subscribe requests to the list. Use the <br>> www interface or send it to gmx-users-request@gromacs.org.<br>> Can't post? Read http://www.gromacs.org/mailing_lists/users.php<br><br><hr>What can you do with the new Windows Live? <a>Find out</a><br /><hr />Insert movie times and more without leaving HotmailĀ®. <a href='http://windowslive.com/Tutorial/Hotmail/QuickAdd?ocid=TXT_TAGLM_WL_HM_Tutorial_QuickAdd1_052009' target='_new'>See how.</a></body>
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