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.htm