<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div>hello all,<br data-mce-bogus="1"></div><div>i am trying to apply electric field with saw-tooth like potential to bilayer graphene. but i face with problem in relaxing coordinates and lattice parameters. it doesnt converged.<br data-mce-bogus="1"></div><div>please help me. my input file is:</div><div> &CONTROL<br> calculation = 'vc-relax' ,<br> restart_mode = 'from_scratch' ,<br> wf_collect = .true. ,<br> outdir = './out' ,<br> wfcdir = './out' ,<br> pseudo_dir = './' ,<br> verbosity = 'high' ,<br> etot_conv_thr = 1.0D-6 ,<br> forc_conv_thr = 1.0D-3 ,<br> tstress = .true. ,<br> tprnfor = .true. ,<br> tefield = .true. ,<br>dipfield=.true.,<br> /<br> &SYSTEM<br> ibrav = 4,<br> celldm(1) = 4.6487259319,<br> celldm(3) = 10.162601626,<br> nat = 4,<br> ntyp = 1,<br> ecutwfc = 30 ,<br> ecutrho = 180 ,<br> occupations = 'smearing' ,<br> degauss = 0.0100 ,<br> smearing = 'gaussian' ,<br> input_dft = 'vdW-DF' ,<br>edir = 3 ,<br> emaxpos = 0.7833 ,<br> eopreg = 0.2167 ,<br> eamp = 0.019447 ,<br> /<br> &ELECTRONS<br> electron_maxstep = 200,<br> conv_thr = 1.0d-6 ,<br> mixing_mode = 'plain' ,<br> mixing_beta = 0.3 ,<br> diagonalization = 'cg' ,<br> /<br> &IONS<br> ion_dynamics = 'bfgs' ,<br> /<br> &CELL<br> cell_dynamics = 'bfgs' ,<br>cell_factor = 5d0 ,<br> /<br>ATOMIC_SPECIES<br> C 12.01100 C.blyp-mt.UPF <br>ATOMIC_POSITIONS crystal <br> C 0.333333330 0.666666660 0.5666 <br> C 1.000000000 0.000000000 0.5666 <br> C 0.666666660 0.333333330 0.4334 <br> C 1.000000000 0.000000000 0.4334 <br>K_POINTS automatic <br>16 16 1 0 0 0 <br><br data-mce-bogus="1"></div></div></body></html>