<div>Hi, all</div> <div>In fact, I want to verify the hygroscopic of lithium bromide solution, so I want to make some water moleculars in the vapor region. But I found that at 0.008bar, 303K and very small box(the unit of the length of the box is nm), there may be zero vapor moleculars. Thus I think I cannot simulate in this pressure or this temperature. Can you give me some advice on this topic? thank you very much.</div> <div> </div> <div>Re:<BR><BR>Hi, beibei<BR><BR>The first point made by Mark is to check whether volume stabilizes when<BR>the system is subjected to NPT simulation.<BR><BR>Regards,<BR>Yang Ye<BR><BR>Mark Abraham wrote:<BR>> Please leave GROMACS-related correspondence on the GROMACS mailing list.<BR>> That way others can follow and contribute to the discussion, and it is<BR>> archived for people to search later.<BR>><BR>> Mark<BR>><BR>> -------- Original Message --------<BR>> Subject: some questions about
simulate a liquid-vapor interface of a<BR>> solution, many thanks<BR>> Date: Thu, 12 Jun 2008 22:40:05 +0800 (CST)<BR>> From: beibei <PARABOLA1981@YAHOO.COM.CN><BR>> To: mark.abraham@anu.edu.au<BR>><BR>><BR>><BR>> Hi, Mark<BR>> Thank you very much to your reply. I cannot undersand some points in<BR>> your reply. How to compute the volume that will lead to this pressure<BR>> when the system is equilibrated? in addition, do you mean the sysytem is<BR>> sandwich box or the cubic box?<BR>> looking forward to your advice. Thank you very much.<BR>> Best wishes.<BR>><BR>><BR>> Beibei<BR>><BR>> beibei wrote:<BR>> <BR>>> Hi all,<BR>>> I want to simulate the liquid-vapor interface of I lithium<BR>>> bromide solution at 303K and 0.008bar. First I put the solution to a<BR>>> cubic box and used NPT ensemble to simulate. Then, I enlarged the box<BR>>> <BR>> to<BR>> <BR>>> form two
liquid-vapor interface,and used NVT ensemble, but the<BR>>> <BR>> pressure<BR>> <BR>>> is not 0.008 bar.<BR>>> <BR>><BR>> You need to determine a volume that will lead to this pressure when the<BR>> system is equilibrated. Then you need to measure for long enough to get<BR>> a meaningful average pressure. Trial and error might be the most<BR>> effective approach. Best of luck!<BR>><BR>> <BR>>> If I used NPT emsemble in the second step, the box<BR>>> becomes smaller with the run time.<BR>>> <BR>><BR>> Of course... you won't get phase separation at equilibrium in NPT<BR>> unless<BR>> you happen to be at a critical point. Think about heating and cooling a<BR>> closed and open beaker of real water.<BR>><BR>> <BR>>> I want to know how to do when I<BR>>> want to simulate the liquid-vapor interface of a solution at a low<BR>>> <BR>> pressure.<BR></div><p> 
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