<div>Dear QE users and developers,</div><div><br></div><div>Recently I used vc-relax to optimize Se in the honeycomb structure, but the unit cell goes larger and larger without convergence. To me there must be something wrong with my calculations. Do you have any idea to get everything right?</div><div><br></div><div>Best</div><div>Jibiao Li</div><div>Yangtze Normal University, China</div><div><br></div><div><br></div><div> &CONTROL<br>                 calculation = 'vc-relax' ,<br>                restart_mode = 'from_scratch' ,<br>                      outdir = './' ,<br>                  pseudo_dir = '/home/jibiaoli/pseudo/' ,<br>                      prefix = 'Se_hc' ,<br>                     disk_io = 'high' ,<br> /<br> &SYSTEM<br>                       ibrav = 4,<br>                   celldm(1) = 4.7126,<br>                   celldm(3) = 8.41,<br>                         nat = 2,<br>                        ntyp = 1,<br>                     ecutwfc = 41 ,<br>                     ecutrho = 180 ,<br>                 occupations = 'smearing' ,<br>                     degauss = 0.05D0 ,<br>                    smearing = 'methfessel-paxton' ,<br>                    vdw_corr = 'grimme-d2' ,<br> /<br> &ELECTRONS<br>                 mixing_beta = 0.3D0 ,<br>             diagonalization = 'david' ,<br> /<br> &IONS<br>                ion_dynamics = 'bfgs' ,<br> /<br> &CELL<br>               cell_dynamics = 'bfgs' ,<br>                 cell_dofree = '2Dxy' ,<br> /<br>ATOMIC_SPECIES<br>   Se   78.96100  Se.pbe-van.UPF <br>ATOMIC_POSITIONS angstrom <br>   Se      1.246899765    0.719897900    0.000000000    <br>   Se      0.000000000    0.000000000    0.000000000     0 0 0<br>K_POINTS automatic <br>  9 9 1   0 0 0 <br><br></div>