rlist 1.3 did the trick, thanks. Why did I not see this problem with PME-switch?<div><br></div><div>Thanks,</div><div><br></div><div>Ilya</div><div><br><br><div class="gmail_quote">2009/4/1 Berk Hess <span dir="ltr"><<a href="mailto:gmx3@hotmail.com">gmx3@hotmail.com</a>></span><br>
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<br><br>> Date: Wed, 1 Apr 2009 14:15:05 +1100<br>> From: <a href="mailto:Mark.Abraham@anu.edu.au" target="_blank">Mark.Abraham@anu.edu.au</a><br>> To: <a href="mailto:gmx-users@gromacs.org" target="_blank">gmx-users@gromacs.org</a><br>
> Subject: Re: [gmx-users] Energy Conservation with 4fs timestep<div class="im"><br>> <br>> Joe Joe wrote:<br>> > Hi,<br>> > <br>> > I get good conservation when running NVE in gromacs with 4 fs when I use <br>
> > PME-switch for electrostatics but not so good when I use switch. Any <br>> > thoughts why that would be? Params shown below.<br>> <br>> Finite cutoffs (such as used with "switch") are intrinsically unlikely <br>
> to conserve energy.<br>> <br>> Mark<br><br></div>That is not right.<br>Finite cut-off's such as switch and shift are purposely designed to conserve energy.<br>Switch is not particularly good though, since the switching introduces large forces.<br>
I would advise to use PME-switch or reaction-field-zero for electrostatics and shift for vdw.<br><br>But the main problem in your setup seems to be the 0.1 nm buffer between the cut-off<br>and rlist. In general you will need a buffer of 0.25 to 0.3 nm.<br>
You can use rlist=-1 to get exact integration and then vary rlist to get a reasonable<br>neighborlist update frequency (somewhere around 10 steps).<br>We should automate the choice of rlist such that the user does not need to worry<br>
about this.<br><font color="#888888"><br>Berk<br></font><div class="hm"><br><br><br><br><hr>Express yourself instantly with MSN Messenger! <a href="http://clk.atdmt.com/AVE/go/onm00200471ave/direct/01/" target="_blank">MSN Messenger</a></div>
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