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<p class="MsoNormal"><span style="font-weight:normal">Dear gmx-user,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal">I would like to simulate an isolated drop of water (without PBC). To prevent water molecules form evaporation I would like to create a spherical constraint around the system. In recent article in PNAS
(Caleman, Hub, van Maaren, van der Spoel, v. 108, 6838 (2011)) where the authors considered similar system it is mentioned that:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:"AdvOT10f0fcb1","sans-serif";font-weight:normal">“To avoid such evaporation, we applied a spherical flat-bottom quadratic potential acting on the water. That potential
was implemented as an additional force </span><span style="font-size:10.0pt;font-family:"AdvOT92137dae.I","sans-serif";font-weight:normal">F
</span><span style="font-size:10.0pt;font-family:"AdvOT10f0fcb1","sans-serif";font-weight:normal">pointing toward the COM of the droplet…”<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal">Could anybody give a hint how this approach can be realized in GROMACS? I looked through the manual, but did not find clear answer how to implement such a force.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal">Thank you very much in advance.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-weight:normal">Mikhail<o:p></o:p></span></p>
<p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Arial","sans-serif";font-weight:normal">=============================================<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Arial","sans-serif";font-weight:normal">Dr Mikhail Stukan<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";font-weight:normal">Schlumberger Dhahran Carbonate Research Center,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";font-weight:normal">Dhahran Techno Valley - KFUPM,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";font-weight:normal">P.O. Box 39011, Dammam / Doha Camp 31942,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";font-weight:normal">Kingdom of Saudi Arabia</span><span style="font-family:"Arial","sans-serif";font-weight:normal"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Arial","sans-serif";font-weight:normal">Tel: +966 3 331 6182<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Arial","sans-serif";font-weight:normal">Fax:+966 3 330 0845<br>
<a href="mailto:mstukan@slb.com"><span style="color:blue">mstukan@slb.com</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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