Hi Erik.<br><br>I was thinking something about it exactly now. I mean, Berk quoted that the scalling goes with beta/tau in Berendsen, and with beta/tay^2 in Parrinello. I mean, in a similar implementation, how should it go for a nosè implementation?
<br><br>Also, what would be a good value for tau_p so? I was looking in, for exemple, the "spider tutorial", and there they use a tau_p value of .5, not so different from my value of .4 (and not .1).<br><br>Finally: it also mean that if I choose a beta and tau_p pair which yelds a too low value, it won't really affect the equilibrium density of the system, correct?
<br><br>Thanks a lot in advance!<br><br>Sincerally yours,<br><br>Jones<br><br><div><span class="gmail_quote">On 5/3/07, <b class="gmail_sendername">Erik Lindahl</b> <<a href="mailto:lindahl@cbr.su.se">lindahl@cbr.su.se
</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div style="">Hi,<div><br><div><span class="q"><div>On May 3, 2007, at 12:37 PM, Jones de Andrade wrote:
</div><br><blockquote type="cite">Hi Berk! Thanks for your so fast answer!<br><br>I'll try to look for a different tau_p. I would really feel 4 ps a too high value, even for water systems, but will look around before decision. Anyway, I'm still concerned about the compressibility value.
<br><br>Long time ago in this list I came to this question, and this is how this ended:<br><br><pre><i></i>><i> Hi,<br></i>><i><br></i>><i> Just use the water value for any liquid system (5e-5 or so).<br></i>>
<br><i><br></i>><i> As the manual explains, it only affects the coupling time, not the<br></i>><i> equilibrium pressure.<br></i>></pre></blockquote><div><br></div></span>This is valid for long times, and (as always for pressure) assumes the external coupling to be clearly slower than the internal dynamics. I have no idea how Amber or DLPOLY sets their tau_t with Nose or Parinello-Rahman, but as specified in the Gromacs manual we use the period of average fluctuations at equilibrium. With tau=
0.1 the system will very likely never reach that equilibrium.</div><div><br></div><div>Cheers,</div><span class="sg"><div><br></div><div>Erik</div><div><br></div></span></div></div><br>_______________________________________________
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