<div dir="ltr"><div dir="ltr">Hi Paolo, Lorenzo,<div><br></div><div>Thanks so much for your attention to this matter. I believe this is likely a bug in QE, and have made an issue post in gitlab. <a href="https://gitlab.com/QEF/q-e/issues/108">https://gitlab.com/QEF/q-e/issues/108</a></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Apr 30, 2019 at 3:03 PM Paolo Giannozzi <<a href="mailto:p.giannozzi@gmail.com">p.giannozzi@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr">On Tue, Apr 30, 2019 at 2:50 PM Daniel Marchand <<a href="mailto:daniel.marchand@gmail.com" target="_blank">daniel.marchand@gmail.com</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">Thanks again. So for the BFGS output, for whatever reason there is a final SCF step, I"m not sure why. </div></div></div></div></div></blockquote><div><br></div><div>it's explained in the message preceding the final step</div><div> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">And yes, correct, the damped_dyanmics(n=50) ~= "BFGS"(n=14).<div><br>However my concern is that for the "BFGS" the z component of all axis changes, which for my use-case is very bad. However, for damp only the z component of axis 3 (v3_z) is allowed to relax. Unfortunately, in my use case (the one in the attached example) the damp method seems to converge much much slower than BFGS. E.g. for the metrics that would affect my needs:</div><div><br></div><div>grep -A3 CELL_PARAMETERS pw.out.bfgs <fast convergence in cell shape, but we see shifts in the z-component of axis 1 & axis 2, which for my needs is very bad><br></div><div>grep -A3 CELL_PARAMETERS pw.out.damp_pr <slow convergence in cell shape, but we see that the z-component of axis 1 & axis 2 are held fixed, which for my needs is very good></div><div><br></div><div>Is there any way to make bfgs hold the z-component of axis 1 & 2 fixed, like how we see for the damp_pr example? </div><div><br></div><div>Best,</div><div><br></div><div>Daniel </div></div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Apr 30, 2019 at 2:16 PM Lorenzo Paulatto <<a href="mailto:paulatz@gmail.com" target="_blank">paulatz@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">there are several quircks:<br>
<br>
I see you did not specify ion_dynamics="damp" when doing damped <br>
dynamics, I'm not sure what happens of the ions in this case.<br>
<br>
The "BFGS" output you sent me is contains 14 steps of BFGS optimization, <br>
followed by one step of (damped?) molecular dynamics<br>
<br>
The damped dynamics run stops because it reaches the maximum of 50 <br>
iterations (nstep=50) not because it has converged, but the cell it <br>
obtains is pretty much identical to the BFGS one<br>
<br>
hth<br>
<br>
On 30/04/2019 13:55, Daniel Marchand wrote:<br>
> Thanks, Lorenzo, for the rapid response. I have a bit of a concern w.r.t <br>
> the z-only relaxation. When I use BFGS the z component of all the axis <br>
> are allowed to relax. However, I do not want this, I want only the z <br>
> component of axis 3 (v3_z) to be moved, as per the description in the <br>
> documentation. This only seems possible with the damp algorithm. Here I <br>
> have attached sample input for both the bfgs and damp_pr algorithms <br>
> <a href="https://drive.google.com/file/d/17Bt8HHL55yG75cba6awvl8E_wo20KDYI/view?usp=sharing" rel="noreferrer" target="_blank">https://drive.google.com/file/d/17Bt8HHL55yG75cba6awvl8E_wo20KDYI/view?usp=sharing</a>. <br>
> Perhaps I have one of the settings wrong?<br>
> <br>
> Best,<br>
> <br>
> Daniel<br>
> <br>
> <br>
> On Tue, Apr 30, 2019 at 1:07 PM Lorenzo Paulatto <<a href="mailto:paulatz@gmail.com" target="_blank">paulatz@gmail.com</a> <br>
> <mailto:<a href="mailto:paulatz@gmail.com" target="_blank">paulatz@gmail.com</a>>> wrote:<br>
> <br>
> > 1) Is this still the case? When I enable this setting in my own<br>
> > calculations (QE v6.3) I see the cell does indeed allow only<br>
> > z-relaxation in the cell, but it does so for all the lattice<br>
> directions<br>
> > rather than just the a_3 lattice direction.<br>
> <br>
> In general cell_dofree works with BFGS, but it is true that some times<br>
> damped dynamics is more reliable.<br>
> <br>
> I.e. I recently did some relaxations with cell_dofree="shape", as BFGS<br>
> was not findign the minimum for some volumes, I just put<br>
> cell_dynamics="damp-pr"<br>
> ion_dynamics = 'damp'<br>
> with everything default.<br>
> <br>
> cheers<br>
> <br>
> -- <br>
> Lorenzo Paulatto - Paris<br>
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-- <br>
Lorenzo Paulatto - Paris<br>
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