<div dir="ltr"><div>Dear Webb Foo,</div><div><br></div><div>centroid constraints/restraints have been implemented recently and will be available in the upcoming new CP2K release v7.1.</div><div><br></div><div>The input is very similar to normal MD simulations. I would recommend using the exact integrator in
combination with the PILE thermostat.</div><div>Example inputs (which need to be adapted carefully)
can be found under tests/Pimd/regtest-1 and regtest-2: h2o_pint_constraints_exact.inp
for the constraints and w512_pint_pile.inp for
the PILE thermostat.</div><div>Note that regtests are usually
optimized to trigger as many parts of the code as
possible and are not always best simulation practice. </div><div><br></div><div>Best, Christoph<br></div><div><br></div>On Sunday, June 2, 2019 at 3:21:00 AM UTC+2, Webb Foo wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Hi <span style="color:rgb(0,0,0);font-family:Helvetica;font-size:12px">Thomas,</span><div><font face="Helvetica" color="#000000"><span style="font-size:12px">Thanks for your reply. And I'll have a try.</span></font></div><div><font face="Helvetica" color="#000000"><span style="font-size:12px"><br></span></font></div><div><font face="Helvetica" color="#000000"><span style="font-size:12px">Cheers,</span></font></div><div><font face="Helvetica" color="#000000"><span style="font-size:12px">Webb<br></span></font><br>在 2019年5月31日星期五 UTC+8上午4:52:40，tkuehne写道：<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Dear Webb Foo, <div><br></div><div>using constrained MD the free energy profile can be computed in terms of the potential of mean force by means of the ensemble </div><div>average of the Lagrange multipliers to constrain your reaction coordinate. You will find a particular good description in the SI of</div><div>the following paper: <a href="https://www.pnas.org/content/104/8/2626.short" rel="nofollow" target="_blank" onmousedown="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fwww.pnas.org%2Fcontent%2F104%2F8%2F2626.short\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFLuIlfIaf3bvahh7e8sdH8uKl3Rw';return true;" onclick="this.href='https://www.google.com/url?q\x3dhttps%3A%2F%2Fwww.pnas.org%2Fcontent%2F104%2F8%2F2626.short\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNFLuIlfIaf3bvahh7e8sdH8uKl3Rw';return true;">https://www.pnas.org/<wbr>content/104/8/2626.short</a></div><div>However, when using PIMD, in my opinion the constraint has to be enforced on the ring-polymer centroid, which most likely </div><div>requires a little bit of coding. </div><div><br></div><div>Best, </div><div>Thomas Kühne</div><div><br><div><blockquote type="cite"><div>Am 30.05.2019 um 10:16 schrieb Webb Foo <<a rel="nofollow">l...@gmail.com</a>>:</div><br><div><div dir="ltr">Hello everyone,<div><br clear="all"><div>Can you explain me how to estimate the free energy profile from a pimd simulation, like constrained MD?</div></div></div><div><br></div>

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