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<body class='hmmessage'><div dir='ltr'>David,<div><pre style="line-height: 21.2999992370605px; white-space: normal; font-family: 'Segoe UI', 'Segoe UI Web Regular', 'Segoe UI Symbol', 'Helvetica Neue', 'BBAlpha Sans', 'S60 Sans', Arial, sans-serif; color: rgb(68, 68, 68); font-size: 15px; background-color: rgb(255, 255, 255);">You asked:</pre><pre style="line-height: 21.2999992370605px; white-space: normal; font-family: 'Segoe UI', 'Segoe UI Web Regular', 'Segoe UI Symbol', 'Helvetica Neue', 'BBAlpha Sans', 'S60 Sans', Arial, sans-serif; color: rgb(68, 68, 68); font-size: 15px; background-color: rgb(255, 255, 255);">>These forces are used to compute the virial and hence the pressure.<br style="line-height: 21.2999992370605px;">>Having said that, if you are interested in improved methods for long <br style="line-height: 21.2999992370605px;">>range forces, why are you looking at reaction fields?</pre><div>I am interested in isotropic liquids and crystals. In particular,</div><div>phase transitions of pure liquids without liquid-solid and liquid-vapor</div><div>coexistence(if such think is possible). Under these conditions, reaction field </div><div>methods give <span style="font-size: 12pt;">results comparable to Ewald summations at a fraction of the </span></div><div><span style="font-size: 12pt;">computational </span><span style="font-size: 12pt;">cost.</span></div><div><br></div><div>To give you a little bit more context, in case you are curious, I am interested in </div><div>reproducing and <span style="font-size: 12pt;">understanding in more depth the problem & debate presented in the following</span></div><div><span style="font-size: 12pt;">article:</span></div><div><a href="http://physicsworld.com/cws/article/news/2013/mar/26/why-water-prefers-the-single-life" target="_blank">http://physicsworld.com/cws/article/news/2013/mar/26/why-water-prefers-the-single-life</a></div><div><br></div><div>Down the road, I would like to apply what I learn to improvements for long range methods</div><div>in the simulation of larger biomolecules an other non-isotropic system. Reactions fields</div><div>is just the beginning.</div><div><br></div><div>Also, I am running a small test, and the forces given by gromacs differ from my own calculations</div><div>for a simple water system using a simple R script. I assume I am missing something. It is probably</div><div>the cut-off scheme that Berk mentioned. </div><div><br></div><div>Thanks for your response</div><br><div>Noel Carrascal</div></div> </div></body>
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