It is because you have an uneven number of electrons in your system. This means you have an unpaired electron (so your system has a radical character) which should not be described without a spin-polarized calculation. But you're right this also means your system is paramagnetic.
Regards Dominik M.Sc. Dominik Voigt PhD Student Münster University of Applied Sciences Email: [email protected] > Dear Dominik > > Thank you very much for your reply.In fact, I added a hydroxyl group above > the graphene sheet to build a simple hydroxylated graphene model,and the > oxygen atom is directly above the carbon atom and the distance is about > 1.45 angstroms.I want to know why I need to do spin polarization > calculation for this system,is it because the presence of the hydroxyl > group makes the graphene system magnetic? > > > Wei gui > School of Mechanical Engineering?Chongqing University, China > >> -----????----- >> ???: [email protected] >> ????: 2019-04-04 20:18:15 (???) >> ???: "Quantum Espresso users Forum" <[email protected]> >> ??: >> ??: Re: [QE-users] Optimization does not converge >> >> I'm not sure but I think it has to do with the fact that you have an >> unpaired electron in your system. You haven't defined the tot_charge of >> your system, therefor the default value of tot_charge=0 means that you >> have an OH radical adsorbed/bonded to the graphene layer. If that's >> what >> you want you should specify nspin and tot_magnetization. If you want >> instead a hydroxy-ion (OH-) adsorbed on to the graphene layer you >> should >> set the tot_charge=-1. >> >> But as I said I'm not sure about this, so maybe there are some other >> suggestions from users with more experience in this area of expertise? >> >> Best Regards >> >> Dominik >> >> M.Sc. Dominik Voigt PhD Student >> Münster University of Applied Sciences >> Email: [email protected] >> >> >> > Dear QE users, >> > I am trying to optimize a single-layer graphene connected to a >> hydroxyl >> > group.After 48 scf cycles,the optimization result has never reached >> the >> > convergence value,the force of some atoms is always greater than the >> > convergence threshold.But when I connect an epoxy group instead of a >> > hydroxyl group on the graphene sheet, the optimization can reach >> > convergence after 24 scf cycles.Does anyone know the reason for this? >> > Any suggestions would be greatly appreciated. >> > Thank you. >> > >> > >> > &control >> > calculation = 'relax', >> > prefix='QJ1GO', >> > pseudo_dir = '/public/home/duan1/GuiWei/pseudo/', >> > outdir='/public/home/duan1/GuiWei/tempdir/' >> > tstress = .true. >> > tprnfor = .true. >> > etot_conv_thr=1.0D-4 >> > forc_conv_thr=1.0D-3 >> > / >> > &system >> > ibrav= 0, >> > nat=66, >> > ntyp=3, >> > >> > occupations='smearing', >> > smearing='mp', >> > degauss=0.02, >> > >> > >> > ecutwfc =40.0 >> > ecutrho =320.0 >> > >> > vdw_corr='DFT-D' >> > london_s6 = 0.75 >> > >> > >> > / >> > &electrons >> > conv_thr = 1.0d-8 >> > mixing_beta = 0.2 >> > mixing_mode = 'local-TF' >> > mixing_ndim=16 >> > electron_maxstep=200 >> > / >> > &IONS >> > ion_dynamics='bfgs' >> > / >> > CELL_PARAMETERS angstrom >> > 19.680000000000003 0.000000000000010 0.000000000000000 >> > 0.000000000000000 8.521689973238882 0.000000000000000 >> > 0.000000000000000 0.000000000000000 25.000000000000000 >> > ATOMIC_SPECIES >> > C 12.0107 C.pbe-rrkjus.UPF >> > O 16.00 O.pbe-rrkjus.UPF >> > H 1.00 H.pbe-rrkjus.UPF >> > ATOMIC_POSITIONS crystal >> > C 0.0000000000000000 0.0000000000000000 0.2164000000000000 >> > C 0.1250000000000000 -0.0000000000000000 0.2164000000000000 >> > C 0.0625000000000000 0.2499999999999999 0.2164000000000000 >> > C 0.0000000000000000 0.4999999999999999 0.2164000000000000 >> > C 0.2500000000000000 -0.0000000000000002 0.2164000000000000 >> > C 0.1875000000000000 0.2499999999999999 0.2164000000000000 >> > C 0.1250000000000000 0.4999999999999998 0.2164000000000000 >> > C 0.0624999999999998 0.7499999999999989 0.2164000000000000 >> > C 0.3750000000000000 -0.0000000000000002 0.2164000000000000 >> > C 0.3125000000000000 0.2500000000000000 0.2164000000000000 >> > C 0.2500000000000000 0.4999999999999999 0.2164000000000000 >> > C 0.1875000000000000 0.7499999999999989 0.2164000000000000 >> > C 0.5000000000000000 -0.0000000000000002 0.2164000000000000 >> > C 0.4375000000000000 0.2500000000000000 0.2164000000000000 >> > C 0.3750000000000000 0.4999999999999999 0.2164000000000000 >> > C 0.3125000000000000 0.7499999999999988 0.2164000000000000 >> > C 0.6250000000000000 -0.0000000000000004 0.2164000000000000 >> > C 0.5625000000000000 0.2500000000000000 0.2164000000000000 >> > C 0.5000000000000000 0.4999999999999999 0.2164000000000000 >> > C 0.4375000000000000 0.7499999999999988 0.2164000000000000 >> > C 0.7500000000000000 -0.0000000000000004 0.2164000000000000 >> > C 0.6875000000000000 0.2499999999999999 0.2164000000000000 >> > C 0.6250000000000000 0.4999999999999999 0.2164000000000000 >> > C 0.5625000000000000 0.7499999999999988 0.2164000000000000 >> > C 0.8750000000000000 -0.0000000000000004 0.2164000000000000 >> > C 0.8125000000000000 0.2499999999999990 0.2164000000000000 >> > C 0.7500000000000000 0.4999999999999999 0.2164000000000000 >> > C 0.6875000000000000 0.7499999999999989 0.2164000000000000 >> > C 0.9375000000000000 0.2499999999999990 0.2164000000000000 >> > C 0.8750000000000000 0.5000000000000000 0.2164000000000000 >> > C 0.8125000000000000 0.7499999999999988 0.2164000000000000 >> > C 0.9375000000000000 0.7499999999999988 0.2164000000000000 >> > C 0.0624999725702591 0.0833332967603452 0.2164000000000000 >> > C -0.0000000274297411 0.3333332967603450 0.2164000000000000 >> > C 0.1874999725702590 0.0833332967603452 0.2164000000000000 >> > C 0.1249999725702590 0.3333332967603450 0.2164000000000000 >> > C 0.0624999725702589 0.5833332967603438 0.2164000000000000 >> > C -0.0000000274297409 0.8333332967603447 0.2164000000000000 >> > C 0.3124999725702590 0.0833332967603452 0.2164000000000000 >> > C 0.2499999725702590 0.3333332967603450 0.2164000000000000 >> > C 0.1874999725702590 0.5833332967603448 0.2164000000000000 >> > C 0.1249999725702590 0.8333332967603447 0.2164000000000000 >> > C 0.4374999725702590 0.0833332967603452 0.2164000000000000 >> > C 0.3749999725702590 0.3333332967603450 0.2164000000000000 >> > C 0.3124999725702590 0.5833332967603448 0.2164000000000000 >> > C 0.2499999725702590 0.8333332967603447 0.2164000000000000 >> > C 0.5624999725702590 0.0833332967603451 0.2164000000000000 >> > C 0.4999999725702591 0.3333332967603449 0.2164000000000000 >> > C 0.4374999725702590 0.5833332967603438 0.2164000000000000 >> > C 0.3749999725702590 0.8333332967603447 0.2164000000000000 >> > C 0.6874999725702590 0.0833332967603451 0.2164000000000000 >> > C 0.6249999725702590 0.3333332967603450 0.2164000000000000 >> > C 0.5624999725702590 0.5833332967603447 0.2164000000000000 >> > C 0.4999999725702591 0.8333332967603448 0.2164000000000000 >> > C 0.8124999725702590 0.0833332967603451 0.2164000000000000 >> > C 0.7499999725702590 0.3333332967603450 0.2164000000000000 >> > C 0.6874999725702600 0.5833332967603440 0.2164000000000000 >> > C 0.6249999725702590 0.8333332967603438 0.2164000000000000 >> > C 0.9374999725702590 0.0833332967603450 0.2164000000000000 >> > C 0.8749999725702590 0.3333332967603450 0.2164000000000000 >> > C 0.8124999725702600 0.5833332967603438 0.2164000000000000 >> > C 0.7499999725702590 0.8333332967603438 0.2164000000000000 >> > C 0.9374999725702590 0.5833332967603438 0.2164000000000000 >> > C 0.8749999725702601 0.8333332967603448 0.2164000000000000 >> > O 0.5008325506691220 0.4975899051684459 0.2743438844378600 >> > H 0.4505865611121930 0.4983293698599460 0.2875531708238770 >> > K_POINTS automatic >> > 2 2 1 0 0 0 >> > >> > >> > Wei gui >> > School of Mechanical Engineering?Chongqing University, China >> > >> > >> > >> > _______________________________________________ >> > users mailing list >> > [email protected] >> > https://lists.quantum-espresso.org/mailman/listinfo/users >> >> >> _______________________________________________ >> users mailing list >> [email protected] >> https://lists.quantum-espresso.org/mailman/listinfo/users > _______________________________________________ > users mailing list > [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
