Dear, Dr. Kumar Yes. I checked the geometry before and after the 'relax' which looks ok ... The atomic distance between neighboring atoms about 12A along x-direction and about 24A along y-direction.. The vacuum region along x-direction might not be large enough but I believe it wouldn't be a problem having considered that the 10~15A of vacuum region usually is accepted. (Please correct me if I'm wrong.) Could I ask what you mean by 'it is far from the Si-H system' ?
Thank you very much. Best regards, Jiseok Kim On 9/5/12 2:51 AM, "pw_forum-request at pwscf.org" <pw_forum-request at pwscf.org> wrote: >Send Pw_forum mailing list submissions to > pw_forum at pwscf.org > >To subscribe or unsubscribe via the World Wide Web, visit > http://www.democritos.it/mailman/listinfo/pw_forum >or, via email, send a message with subject or body 'help' to > pw_forum-request at pwscf.org > >You can reach the person managing the list at > pw_forum-owner at pwscf.org > >When replying, please edit your Subject line so it is more specific >than "Re: Contents of Pw_forum digest..." > > >Today's Topics: > > 1. Re: Pw_forum Digest, Vol 63, Issue 8 (Ramesh Kumar) > > >---------------------------------------------------------------------- > >Message: 1 >Date: Wed, 5 Sep 2012 09:02:11 +0530 >From: Ramesh Kumar <rameshchitumalla at gmail.com> >Subject: Re: [Pw_forum] Pw_forum Digest, Vol 63, Issue 8 >To: pw_forum at pwscf.org >Message-ID: > <CAO1fJnvo6EhnZUdMYhURsg2Y9fDQimng16PYiqLUOUCgfCXFFw at mail.gmail.com> >Content-Type: text/plain; charset="iso-8859-1" > >Dear JISEOK KIM, > >Did you check/visualize your geometry ? > >The Box is too small and it is far from the Si-H system. > > > > >> I'm having a difficulty on a geometry optimization using 'vc-relax'. >> I searched forum threads and followed various suggestions but the 'Total >> force' still does not converge.. >> (but the pressures seems to be converged) >> >> The job steps I've taken as follows, >> >> 1. optimized k-point and ecutwfc. >> 2. optimized lattice parameter using Murnaghan fitting. >> 3. 'relax' the geometry using the lattice constant obtained from step2, >> >> ---------------------------------------------- >> &control >> calculation = 'relax', >> restart_mode = 'from_scratch', >> prefix = '$NAME', >> pseudo_dir = '$PSEUDO_DIR/', >> outdir = '$OUT_DIR/', >> wf_collect = .TRUE. >> tstress = .TRUE. >> tprnfor = .TRUE. >> etot_conv_thr = 1.d-7 >> forc_conv_thr = 1.d-6 >> nstep = 1000 >> / >> &system >> ibrav = 0, >> celldm(1) = 10.3345 >> nat = 18, >> ntyp = 2, >> ecutwfc = 80.0, >> / >> &electrons >> diagonalization = 'cg', >> mixing_mode = 'plain', >> mixing_beta = 0.7, >> conv_thr = 1.0d-10, >> / >> &ions >> ion_dynamics = 'bfgs' >> bfgs_ndim = 3 >> / >> ATOMIC_SPECIES >> Si 28.086 Si.pbe-rrkj.UPF >> H 1.0079 H.pbe-vbc.UPF >> CELL_PARAMETERS >> .......... >> > .......... > >> K_POINTS automatic >> 1 1 16 0 0 0 >> ---------------------------------------------- >> >> >> 4. check if 'Total force' is converged -> OK. >> 5. Take the final atomic coordinates from step4. >> 6. Run 'vc-relax' as, >> >> ---------------------------------------------- >> &control >> calculation = 'vc-relax', >> restart_mode = 'from_scratch', >> prefix = '$NAME', >> pseudo_dir = '$PSEUDO_DIR/', >> outdir = '$OUT_DIR/', >> wf_collect = .TRUE. >> tstress = .TRUE. >> tprnfor = .TRUE. >> etot_conv_thr = 1.d-6 >> forc_conv_thr = 1.d-6 >> nstep = 10000 >> / >> &system >> ibrav = 0, >> celldm(1) = 10.3345 >> nat = 18, >> ntyp = 2, >> ecutwfc = 80.0, >> ecfixed = 70.0, >> qcutz = 150.0, >> q2sigma = 4.0, >> / >> &electrons >> diagonalization = 'cg', >> mixing_mode = 'plain', >> mixing_beta = 0.7, >> conv_thr = 1.0d-10, >> / >> &ions >> ion_dynamics = 'bfgs' >> bfgs_ndim = 3 >> / >> &cell >> cell_dynamics = 'bfgs' >> press_conv_thr = 0.1d0 >> press = 0.d0 >> cell_factor = 2.d0 >> / >> ATOMIC_SPECIES >> Si 28.086 Si.pbe-rrkj.UPF >> H 1.0079 H.pbe-vbc.UPF >> --------- >> > ---------- > >> K_POINTS automatic >> 1 1 16 0 0 0 >> ---------------------------------------------- >> >> >> >-- >*With Best Regards: > >* >*CH. Ramesh Kumar >Senior Research Fellow, >Computational Chemistry Lab, >Indian Institute of Chemical Technology(IICT),* >*Tarnaka, ** >Hyderabad. >* >-------------- next part -------------- >An HTML attachment was scrubbed... >URL: >http://www.democritos.it/pipermail/pw_forum/attachments/20120905/302456f4/ >attachment.html > >------------------------------ > >_______________________________________________ >Pw_forum mailing list >Pw_forum at pwscf.org >http://www.democritos.it/mailman/listinfo/pw_forum > > >End of Pw_forum Digest, Vol 63, Issue 9 >***************************************
