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Ali,<div><br class="webkit-block-placeholder"></div><div>On 11 Apr 2008, at 21:12, Ali wrote:</div><div><div><br class="Apple-interchange-newline"><blockquote type="cite"><p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Helvetica" size="3" style="font: 12.0px Helvetica">* I have been using NVE instead of NVT for the umbrella sampling.</font></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Technically the equations for umbrella sampling work only with NVT or</font></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Helvetica" size="3" style="font: 12.0px Helvetica">NPT. Can this be a possible source of the problem?</font></p></blockquote>NVE?!? </div><div>You may want an ensemble with a well defined T for umbrella sampling (you're</div><div>computing free energies!). </div><div>NVE does not guarantee that.</div><div><br><blockquote type="cite"> <p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; min-height: 14.0px"><span class="Apple-style-span" style="-webkit-text-stroke-width: -1; ">* Should the force constant of the biasing potential 'K' be similar to</span></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Helvetica" size="3" style="font: 12.0px Helvetica">the force constant of -kT log (P(r)) ? Or should it work even if the</font></p> <p style="margin: 0.0px 0.0px 0.0px 0.0px"><font face="Helvetica" size="3" style="font: 12.0px Helvetica">force constants are very dissimilar?</font></p> </blockquote></div>Please, have a look at the many papers/books on this topic.</div><div><br class="webkit-block-placeholder"></div><div>Teo</div><div><br></div></body></html>