Dear Meisam, I still don't have a clear idea of how exactly the system fails to converge but since you've hit about 100 electronic steps, it looks to me like a typical case of charge sloshing with oscillating energies. This happens a lot when one or more dimensions of your simulation cell is much larger than the others. Try adding smearing, which sometimes tends to stabilize the convergence (I don't really know why but maybe because it introduces empty states which act as more degrees of freedom the system can explore?) and which is something you should do anyway because you have no idea whether this system would be a metal or not.
As an aside, carbon nanotubes have been widely studied as hydrogen storage materials and by themselves they are not that great. You usually need some metal such as Ti. As a second aside I'd be really surprised if this system held together with that many hydrogens on the inner sides of a NT. Hope this helps. Hande On Fri, 1 Aug 2008, meisam aghtar wrote: > ?&SYSTEM ?????????????????????? ibrav = 4, ?????????????????? celldm(1) = 32, ?????????????????? celldm(3) = 0.251568464, ???????????????????????? nat = 80, ? ??????????????????????ntyp = 2, ???????????????????? ecutwfc = 36 , ???????????????????? ecutrho = 400 , ??????????????????????? ?/ ?&ELECTRONS ?/ ?&IONS ?/ ATOMIC_SPECIES ??? C?? 12.01070? C.pz-vbc.UPF ??? H??? 1.00794? H.vbc.UPF ATOMIC_POSITIONS angstrom C???? 3.91443516? 0.00000000? -1.42000000 C???? 3.16684457? 2.30084726? -1.42000000 C???? 1.20962699? 3.72284906? -1.42000000 C???? -1.209626993.72284906? -1.42000000 C???? -3.166844572.30084726? -1.42000000 C???? -3.914435160.00000000? -1.42000000 C???? -3.16684457-2.30084726-1.42000000 C???? -1.20962699-3.72284906-1.42000000 C???? 1.20962699? -3.72284906-1.42000000 C???? 3.16684457? -2.30084726-1.42000000 C???? 3.72284906? 1.20962699? -0.71000000 C???? 2.30084726? 3.16684457? -0.71000000 C???? 0.00000000? 3.91443516? -0.71000000 C???? -2.300847263.16684457? -0.71000000 C???? -3.722849061.20962699? -0.71000000 C???? -3.72284906-1.20962699-0.71000000 C???? -2.30084726-3.16684457-0.71000000 C???? 0.00000000? -3.91443516-0.71000000 C???? 2.30084726? -3.16684457-0.71000000 C???? 3.72284906? -1.20962699-0.71000000 C???? 3.72284906? 1.20962699? 0.71000000 C???? 2.30084726? 3.16684457? 0.71000000 C???? 0.00000000? 3.91443516? 0.71000000 C???? -2.300847263.16684457? 0.71000000 C???? -3.722849061.20962699? 0.71000000 C???? -3.72284906-1.209626990.71000000 C???? -2.30084726-3.166844570.71000000 C???? 0.00000000? -3.914435160.71000000 C???? 2.30084726? -3.166844570.71000000 C???? 3.72284906? -1.209626990.71000000 C???? 3.91443516? 0.00000000? 1.42000000 C???? 3.16684457? 2.30084726? 1.42000000 C???? 1.20962699? 3.72284906? 1.42000000 C???? -1.209626993.72284906? 1.42000000 C???? -3.166844572.30084726? 1.42000000 C???? -3.914435160.00000000? 1.42000000 C???? -3.16684457-2.300847261.42000000 C???? -1.20962699-3.722849061.42000000 C???? 1.20962699? -3.722849061.42000000 C???? 3.16684457? -2.300847261.42000000 H???? 2.82443516? 0.00000000? -1.42000000 H???? 2.28501604? 1.66016133? -1.42000000 H???? 0.87279846? 2.68619746? -1.42000000 H???? -0.872798462.68619746? -1.42000000 H???? -2.285016041.66016133? -1.42000000 H???? -2.824435160.00000000? -1.42000000 H???? -2.28501604-1.66016133-1.42000000 H???? -0.87279846-2.68619746-1.42000000 H???? 0.87279846? -2.68619746-1.42000000 H???? 2.28501604? -1.66016133-1.42000000 H???? 2.68619746? 0.87279846? -0.71000000 H???? 1.66016133? 2.28501604? -0.71000000 H???? 0.00000000? 2.82443516? -0.71000000 H???? -1.660161332.28501604? -0.71000000 H???? -2.686197460.87279846? -0.71000000 H???? -2.68619746-0.87279846-0.71000000 H???? -1.66016133-2.28501604-0.71000000 H???? 0.00000000? -2.82443516-0.71000000 H???? 1.66016133? -2.28501604-0.71000000 H???? 2.68619746? -0.87279846-0.71000000 H???? 2.68619746? 0.87279846? 0.71000000 H???? 1.66016133? 2.28501604? 0.71000000 H???? 0.00000000? 2.82443516? 0.71000000 H???? -1.660161332.28501604? 0.71000000 H???? -2.686197460.87279846? 0.71000000 H???? -2.68619746-0.872798460.71000000 H???? -1.66016133-2.285016040.71000000 H???? 0.00000000? -2.824435160.71000000 H???? 1.66016133? -2.285016040.71000000 H???? 2.68619746? -0.872798460.71000000 H???? 2.82443516? 0.00000000? 1.42000000 H???? 2.28501604? 1.66016133? 1.42000000 H???? 0.87279846? 2.68619746? 1.42000000 H???? -0.872798462.68619746? 1.42000000 H???? -2.285016041.66016133? 1.42000000 H???? -2.824435160.00000000? 1.42000000 H???? -2.28501604-1.660161331.42000000 H???? -0.87279846-2.686197461.42000000 H???? 0.87279846? -2.686197461.42000000 H???? 2.28501604? -1.660161331.42000000 ??? K_POINTS automatic ? 1 1 8?? 0 0 1 output: ... Total force =???? 0.764727???? Total SCF correction =???? 0.001974 ???? entering subroutine stress ... ????????? total?? stress? (Ry/bohr**3)?????????????????? (kbar)???? P=? -46.33 ? -0.00030189? ?0.00000000?? 0.00000000??????? -44.41????? 0.00????? 0.00 ?? 0.00000000? -0.00020564?? 0.00000000????????? 0.00??? -30.25????? 0.00 ?? 0.00000000?? 0.00000000? -0.00043733????????? 0.00????? 0.00??? -64.33 ???? number of scf cycles??? =?? 5 ???? number of bfgs steps??? =?? 4 ???? energy old????????????? =??? -492.3117315584 Ry ???? energy new????????????? =??? -493.0294336293 Ry ???? CASE: energy_new < energy_old ???? new trust radius??????? =?????? 0.8000000000 bohr ???? new conv_thr??????????? =??? ???0.0000010000 Ry ... ???? iteration # 89???? ecut=??? 36.00 Ry???? beta=0.70 ???? Davidson diagonalization with overlap ???? ethr =? 4.42E-08,? avg # of iterations =? 1.5 ???? total cpu time spent up to now is? 17055.30 secs ???? total energy????????????? =? -493.53120359 Ry ???? Harris-Foulkes estimate?? =? -493.53121645 Ry ???? estimated scf accuracy??? <???? 0.00236176 Ry ???? iteration # 90???? ecut=??? 36.00 Ry???? beta=0.70 ???? Davidson diagonalization with overlap ???? ethr =? 4.42E-08,? avg # of iterations =? 1.0 ???? total cpu time spent up to now is? 17148.87 secs ???? total energy????????????? =? -493.53120039 Ry ???? Harris-Foulkes estimate?? =? -493.53120432 Ry ???? estimated scf accuracy??? <???? 0.00230269 Ry ???? iteration # 91???? ecut=??? 36.00 Ry???? beta=0.70 ???? Davidson diagonalization with overlap ? ----- Original Message ---- From: Hande Ustunel <[email protected]> To: PWSCF Forum <pw_forum at pwscf.org> Sent: Friday, August 1, 2008 12:38:47 PM Subject: Re: [Pw_forum] convergence of relaxation caculation Dear Meisam, You would still need to provide input and output because "doesn't converge" means very little out of context. We need to see what that means. Besides, 5 scf cycles is not very many cycles. Is it possible that you mean atomic steps? Even so, it's still acceptable. Hande On Fri, 1 Aug 2008, meisam aghtar wrote: > Dear Stefano I didn?t change any parameters and they are in default mode. I used automatic meshing BZ,1*1*8.also I have not fixed any position. in output , after 5 scf cycles the system doesn?t converge. I think if I ?disrupt the position it would converge but I don?t know how I could make this system converge. ? ? Thanks for your attention. ? M.aghtar Msc student, physics department of Kashan university? -- Hande Toffoli Department of Physics Office 439 Middle East Technical University Ankara 06531, Turkey Tel : +90 312 210 3264 http://www.physics.metu.edu.tr/~hande _______________________________________________ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -- Hande Toffoli Department of Physics Office 439 Middle East Technical University Ankara 06531, Turkey Tel : +90 312 210 3264 http://www.physics.metu.edu.tr/~hande
