On Tue, Apr 30, 2019 at 2:50 PM Daniel Marchand <[email protected]> wrote:
> Thanks again. So for the BFGS output, for whatever reason there is a final > SCF step, I"m not sure why. > it's explained in the message preceding the final step And yes, correct, the damped_dyanmics(n=50) ~= "BFGS"(n=14). > > 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: > > 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> > 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> > > 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? > > Best, > > Daniel > > On Tue, Apr 30, 2019 at 2:16 PM Lorenzo Paulatto <[email protected]> > wrote: > >> there are several quircks: >> >> I see you did not specify ion_dynamics="damp" when doing damped >> dynamics, I'm not sure what happens of the ions in this case. >> >> The "BFGS" output you sent me is contains 14 steps of BFGS optimization, >> followed by one step of (damped?) molecular dynamics >> >> The damped dynamics run stops because it reaches the maximum of 50 >> iterations (nstep=50) not because it has converged, but the cell it >> obtains is pretty much identical to the BFGS one >> >> hth >> >> On 30/04/2019 13:55, Daniel Marchand wrote: >> > Thanks, Lorenzo, for the rapid response. I have a bit of a concern >> w.r.t >> > the z-only relaxation. When I use BFGS the z component of all the axis >> > are allowed to relax. However, I do not want this, I want only the z >> > component of axis 3 (v3_z) to be moved, as per the description in the >> > documentation. This only seems possible with the damp algorithm. Here I >> > have attached sample input for both the bfgs and damp_pr algorithms >> > >> https://drive.google.com/file/d/17Bt8HHL55yG75cba6awvl8E_wo20KDYI/view?usp=sharing. >> >> > Perhaps I have one of the settings wrong? >> > >> > Best, >> > >> > Daniel >> > >> > >> > On Tue, Apr 30, 2019 at 1:07 PM Lorenzo Paulatto <[email protected] >> > <mailto:[email protected]>> wrote: >> > >> > > 1) Is this still the case? When I enable this setting in my own >> > > calculations (QE v6.3) I see the cell does indeed allow only >> > > z-relaxation in the cell, but it does so for all the lattice >> > directions >> > > rather than just the a_3 lattice direction. >> > >> > In general cell_dofree works with BFGS, but it is true that some >> times >> > damped dynamics is more reliable. >> > >> > I.e. I recently did some relaxations with cell_dofree="shape", as >> BFGS >> > was not findign the minimum for some volumes, I just put >> > cell_dynamics="damp-pr" >> > ion_dynamics = 'damp' >> > with everything default. >> > >> > cheers >> > >> > -- >> > Lorenzo Paulatto - Paris >> > _______________________________________________ >> > Quantum Espresso is supported by MaX >> > (www.max-centre.eu/quantum-espresso >> > <http://www.max-centre.eu/quantum-espresso>) >> > users mailing list [email protected] >> > <mailto:[email protected]> >> > https://lists.quantum-espresso.org/mailman/listinfo/users >> > >> > >> > _______________________________________________ >> > Quantum Espresso is supported by MaX ( >> www.max-centre.eu/quantum-espresso) >> > users mailing list [email protected] >> > https://lists.quantum-espresso.org/mailman/listinfo/users >> > >> >> -- >> Lorenzo Paulatto - Paris >> _______________________________________________ >> Quantum Espresso is supported by MaX (www.max-centre.eu/quantum-espresso) >> users mailing list [email protected] >> https://lists.quantum-espresso.org/mailman/listinfo/users > > _______________________________________________ > Quantum Espresso is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
_______________________________________________ Quantum Espresso is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
