Dear REI Please sign always your posts to this forum with name and scientific affiliation.
> forc_conv_thr = 1.d-6 > etot_conv_thr = 1.d-7, VERY tight convergence criteria. You could never find convergence > celldm(1) = 40.50311907 , Huge distance between your wires. If you want to save time perform a first vc-relax calculation with a shorter distance (i.e., 25~30 a.u.), then use the optimized positions and z lattice parameter to start a new calculation with a longer xy spacing. > ecutwfc =80.0, Probably too high for Si, but I did not test the psudopotential, so I cannot say for sure. Anyway a too high cutoff does not hurt! > diagonalization = 'cg' Why not davidson? cg should be used only when davidson fails > conv_thr = 1.0d-12, VERY VERY tight convergence criterium. You probably do not need such an accuracy on wfcs. 1.0d-8 (which becomes 1.0d-10 around bfgs convergence) is generally more than adequate for vc-relax calculations. > bfgs_ndim = 3, Possibly useless in this case... > cell_dofree = 'xyz' , The most important thing: you should optimize the z parameter only, which is meaningful in the case of your system. Use cell_dofree = 'z' > K_POINTS AUTOMATIC > 1 1 16 0 0 0 You may start with a poorer mesh (i.e. 1 1 4, or 1 1 8), and find convergence on the k-points mesh step by step. It is not mandatory, but it usually saves time... HTH Giuseppe On Tuesday 02 July 2013 05:05:35 REI.BOND wrote: > Dear all, > > (sorry! Since pre- mail has been garbled, it is sent once again. ) > > I have a problem. > > My problem of the 16 atom supercell system ( one-dimension system ), I > am trying to vc-relax. > > First, when it calculates in a supercell, is it amusing that pressure > is applied from a vacuum layer? (in my calculation, vacuums layer is x > and y) > > Then, if cell_dofree = 'xyz' is used, a vacuum layer will become small > rapidly. > > Does my calculation have any problems? > > > Thanks, > > REI > > ---input---- > > &control > calculation='vc-relax' > ! restart_mode='restart', > tprnfor = .true. > tstress = .true. > prefix='110', > pseudo_dir = './', > outdir='./' > forc_conv_thr = 1.d-6 > etot_conv_thr = 1.d-7, > nstep =100000 > / > &system > ibrav=6, > celldm(1) = 40.50311907 , > celldm(3) = 0.180919129 , > ! celldm(3) = 4.362274784 , > nat= 14, > ntyp= 2, > ecutwfc =80.0, > / > &electrons > diagonalization = 'cg' > electron_maxstep = 100 > conv_thr = 1.0d-12, > mixing_beta = 0.2, > / > &ions > bfgs_ndim = 3, > / > &cell > cell_dofree = 'xyz' , > press_conv_thr=0.1 > / > ATOMIC_SPECIES > Si 28.086 Si.pz-vbc.UPF > H 1.00782503207 H.pz-vbc.UPF > ATOMIC_POSITIONS bohr > Si 6.680764370 8.898916109 5.986070989 > Si 9.029846753 5.231537887 5.363083201 > Si 6.680057629 1.564614309 5.986065052 > Si 4.221207325 8.899147367 2.313388654 > Si 1.871413129 5.232223481 2.936367832 > Si 4.220504860 1.564853884 2.313381924 > H 8.432421873 11.126743390 6.027800731 > H 2.468854211 -0.662974560 2.271647941 > H 2.469974729 11.127305994 2.271650709 > H 8.431281864 -0.663551556 6.027799087 > H -0.711612701 5.232463267 1.803772875 > H 1.465680126 5.232255329 5.753598846 > H 11.612877425 5.231282938 6.495661694 > H 9.435578196 5.231491779 2.545852436 > K_POINTS AUTOMATIC > 1 1 16 0 0 0 > > ----out--- > > End of self-consistent calculation (1st) > > > Forces acting on atoms (Ry/au): > > Total force = 0.003197 Total SCF correction = 0.000003 > > > entering subroutine stress ... > > total stress (Ry/bohr**3) (kbar) P= > -0.04 -0.00000100 0.00000000 -0.00000056 -0.15 0.00 > -0.08 0.00000000 -0.00000123 0.00000000 0.00 -0.18 > 0.00 -0.00000056 0.00000000 0.00000137 -0.08 0.00 > 0.20 > > CELL_PARAMETERS (alat= 40.50311907) > 0.999975086 0.000000000 0.000000000 > 0.000000000 0.999969153 0.000000000 > 0.000000000 0.000000000 0.180925314 > > End of self-consistent calculation (23st) > > Forces acting on atoms (Ry/au): Total force = 0.005428 Total SCF correction > = 0.000022 entering subroutine stress ... total stress (Ry/bohr**3) (kbar) > P= 0.39 0.00000356 0.00000000 -0.00000051 0.52 0.00 -0.07 0.00000000 > 0.00000351 0.00000000 0.00 0.52 0.00 -0.00000051 0.00000000 0.00000096 > -0.07 0.00 0.14 CELL_PARAMETERS (alat= 40.50311907) 0.805107566 0.000000000 > 0.000000000 0.000000000 0.809022136 0.000000000 0.000000000 0.000000000 > 0.181542885 ******************************************************** - 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 00015 - Monterotondo Stazione (RM) Tel + 39 06 90672836 - Fax +39 06 90672316 E-mail: <giuseppe.mattioli at ism.cnr.it> ResearcherID: F-6308-2012
