Thanks for the reply, buT I am still thinking that should be a bug in the optimizer, since? I also tried to run my system like a metal and nothing gonna change. If I change the optimization method I can reach easly the convergence. Cheers, Piero?
----- Original Message ----- From: Giuseppe Mattioli <[email protected]> Date: Friday, March 13, 2009 11:21 am Subject: Re: [Pw_forum] roblem with bfgs algorithm optimizer for spin polarized system To: PWSCF Forum <pw_forum at pwscf.org> > > Dear Piero > > > ?&ELECTRONS > > ?/ > The default beta mixing parameter is often too high to fit for > many purposes. > Try to use the keyword mixing_beta = 0.3 (e.g.) within the > &electrons group. > > ?> ???????????????? occupations = 'fixed' , > This is not a good choice (at least in my experience) when you > deal with > system in which the magnetization may change. Try to add a > gaussian or a cold > smearing. > > Yours > > Giuseppe > ? > On Friday 13 March 2009 01:23:46 pc229 at kent.ac.uk wrote: > > > Dear PWscf developers,? > > I am trying to? optimize, on the latest version of the > espresso code > > (v4.0.4 ),? the cell parameter and also the ionic coordinate > of hematite.? > > Initially I treat hematite like an insulator using? the following > > pseudo-potential :Fe.pbe-sp-van_ak.UPF for? Iron and O.pbe- > van_ak.UPF for > > oxygen (I attached the input at the bottom). To optimize? both > atomic> coordinates and cell parameters I used bfgs algorithm . > As you know > > hematite is an open-shell system, and you need to define the spin > > orientation in order to describe it like a ferro-magnetic or > > anti-ferromagnetic system. I choose the anti-ferromagnetic > one, that means? > > to have? the total magnetization equal to 0 every SCF cycle > and absolute > > magnetization ranging from 11-16 (this highly pseudo potential > dependent).> Anyway, for the first SCF cycle the magnetization > carried out is correct, > > while after the first geometry optimization step hematite > starts to lose > > the spin and the energy? also dancing between two value not > allowing the > > SCF to converge. So attempting to managed this problem I try > to run it like > > a metal introducing? a methfessel-paxton? smearing. Nothing > seems to > > change, the SCF of the second optimization step doesn't > converge as > > previously. Then I tried to restart my calculation from the > first point > > coordinates and the first SCF step converged, whilst the next > no as in the > > previous cases . This is very strange and get me frustrated ! > Then I run > > the same calculation changing both optimization algorithm to > damp for the > > ionic coordinate and damp-w for the cell. In this way the SCFs > after the > > first optimization cycle seem to converge with the right > magnetization and > > the next as well. I did also a further trial, because I need > to use the > > bfgs algorithm to optimize my structure. I tried to run the > same system on > > a previous version of espresso (v.2.1.2), and treating it like > a metal? > > (with methfessel-paxton? smering) and using bfgs for ionic > coordinate and > > damp for cell optimization (since bfgs wasn't implemented to > optimize the > > cell parameter in this version) the first SCF? reached the > convergence and > > the following as well. How can I solve it ?? I also read in > the documents > > related to PWscf that bfgs? for optimizing cell parameters (vc- > relax) is > > still in a experimental version. Would it be possible that It > has some > > problem with spin polarized systems?? How can I manage this > problem? I need > > desperately to use bfgs to optimize the hematite. > > > > ?? > > Best Regards, Piero > > > > > > ?&CONTROL > > ?????????????????????? title = 'opt_bulk_PBE_van3.inp' , > > ???????????????? calculation = 'vc-relax' , > > ??????????????? restart_mode = 'from_scratch' , > > ????????????????? wf_collect = .true. , > > ????????????????????? outdir = > > > '/home/pc229/backup/Counts/PWscf/Fe2O3_bulk/PWSCF/Fe2O3_bulk/opt_bulk_PBE_v>an/' > , pseudo_dir = > > > '/home/pc229/backup/Counts/PWscf/Fe2O3_bulk/PWSCF/Fe2O3_bulk/pseudo/' , > > prefix = 'opt_bulk_PBE_van3.inp' , > > ?/ > > ?&SYSTEM > > ?????????????????????? ibrav = 5, > > ?????????????????? celldm(1) = 11.091428, > > ?????????????????? celldm(4) = 0.587237106, > > ???????????????????????? nat = 10, > > ??????????????????????? ntyp = 3, > > ???????????????????? ecutwfc = 50 , > > ?????????????????????? nosym = .true. , > > ??????????????????????? nbnd = 70, > > ?????????????????????? nelec = 100, > > ????????????????? tot_charge = 0.000000, > > ???????????????? occupations = 'fixed' , > > ?????????????????????? nspin = 2 , > > ?? starting_magnetization(1) = 1., > > ?? starting_magnetization(2) = -1., > > ?? starting_magnetization(3) = 0., > > ?????????? tot_magnetization = 0 , > > ?/ > > ?&ELECTRONS > > ?/ > > ?&IONS > > ??????????????? ion_dynamics = 'bfgs' , > > ?/ > > ?&CELL > > ?????????????? cell_dynamics = 'bfgs' , > > ?????????????????????? wmass = 2001.0060 , > > ???????????????? cell_dofree = 'all' , > > ?/ > > ATOMIC_SPECIES > > ?? Fe?? 55.62000? Fe.pbe-sp-van_ak.UPF? > > ? Fe1?? 55.62000? Fe.pbe-sp-van_ak.UPF? > > ??? O?? 15.99000? O.pbe-van_ak.UPF? > > ATOMIC_POSITIONS crystal? > > ? Fe?????? 0.144358141?? 0.144342247?? 0.144393006 > > ? Fe1????? 0.355605889?? 0.355642696?? 0.355656118 > > ? Fe1????? 0.644394003?? 0.644359012?? 0.644344959 > > ? Fe?????? 0.855641399?? 0.855655859?? 0.855605070 > > ? O??????? 0.556470421?? 0.943529173?? 0.250007053 > > ? O??????? 0.250006034?? 0.556470770?? 0.943529639 > > ? O??????? 0.943529367?? 0.250006711?? 0.556470944 > > ? O??????? 0.443532949?? 0.056467967?? 0.749992942 > > ? O??????? 0.749994148?? 0.443532454?? 0.056467520 > > ? O??????? 0.056467649?? 0.749993110?? 0.443532750???? > > K_POINTS automatic? > > ? 4 4 4?? 0 0 0 > > > > > > --? > > Pieremanuele Canepa > > Room 230 > > School of Physical Science? > > Ingram Building > > University of Kent, > > ?Canterbury, > > ?Kent, CT2 7NH? > > United Kingdom > > Cell: +44-7768685833 > > ID Skype: pieremanuele > > ID msn:?pieremanuele83 at hotmail.com > > -------------------------------------------------------- > > -- > ******************************************************** > - Article premier - Les hommes naissent et demeurent > libres et ?gaux en droits. Les distinctions sociales > ne peuvent ?tre fond?es que sur l'utilit? commune > - Article 2 - Le but de toute association politique > est la conservation des droits naturels et > imprescriptibles de l'homme. Ces droits sont la libert?, > la propri?t?, la s?ret? et la r?sistance ? l'oppression. > ******************************************************** > > ?? Giuseppe > Mattioli??????????????????????????? > ?? CNR - ISTITUTO DI STRUTTURA DELLA > MATERIA?? > ?? v. Salaria Km 29,300 - C.P. > 10??????????????? > ?? I 00016 - Monterotondo Stazione > (RM)????????? > ?? Tel + 39 06 90672836 - Fax +39 06 > 90672316??? > ?? E-mail: <giuseppe.mattioli at ism.cnr.it> > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090313/8f287951/attachment-0001.htm
