I think that 22 Ry may be too small for Cu, even with USPP, especially if stress is calculated. try to reduce the mixing_beta.
stefano Christopher O'Brien wrote: > PWSCF users: > I have been struggling for quite some time to perform a vc-relax calculation > on a simple system of 96 Cu atoms. I am confident that the input is correct > as an ion relaxation run converges in one scf cycle to a pressure of -11.54 > kbar with the same parameters as the vc-relax calculation (shown below). > > As seen in the output file, the problem with the vc-relax calculation is that > the SCF error will increase with each iteration. I have tried to remedy this > issue by restricting the maximum movement distance of both the cell and ions > to no avail. Unfortunately, I cannot turn on symmetry as I am using this as a > test case for further calculations of Al-Cu solid solutions. > > Is there anything terribly wrong with my input? Should I impose symmetry > despite the addition of Al to the Cu lattice? > > Thanks for your help. > > > ------------------------------------------------------------------------ > > > > &CONTROL > calculation = 'vc-relax' , > restart_mode = ?from_scratch? , > wf_collect = .false. , > outdir = './' , > pseudo_dir = './' , > prefix = 'Cu' , > forc_conv_thr = 2.0d-2, > etot_conv_thr = 1.0d-3, > tstress = .true. , > verbosity = 'minimal' , > disk_io = 'none' , > tprnfor = .true. , > / > &SYSTEM > ibrav = 8, > celldm(1) = 9.505756, > celldm(2) = 1.735408, > celldm(3) = 4.921944, > nat = 96, > ntyp = 1, > ecutwfc = 22 , > ecutrho = 220 , > nosym = .true. , > occupations = 'smearing' , > degauss = 0.022 , > smearing = 'methfessel-paxton' , > / > &ELECTRONS > conv_thr = 1.0d-5 , > mixing_beta = 0.7 , > / > &IONS > ion_dynamics = 'bfgs' , > / > &CELL > press = 0.0 , > press_conv_thr = 5.0d0, > cell_dofree = 'xyz' , > cell_dynamics = 'bfgs' , > / > ATOMIC_SPECIES > Cu 63.54600 Cu.pw91-n-van_ak.UPF > ATOMIC_POSITIONS (crystal) > Cu 0.000000000 -0.000082163 -0.000018624 > ... > K_POINTS automatic > 6 4 2 1 1 1 1 > > =================================================================== > Christopher J. O'Brien > cjobrien at ncsu.edu > https://sites.google.com/a/ncsu.edu/cjobrien/ > See what I'm citing at http://www.citeulike.org/cjo123 > > Ph.D. Candidate > Computational Materials Group > Department of Materials Science & Engineering > North Carolina State University > __________________________________________________________________ > Please send all documents in PDF, HTML, RTF, DVI, PS or plain text. > For Word documents: Please use the 'Save as PDF' option before sending. > =================================================================== > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
