<div dir="ltr"><div><div><div>Dear All,<br></div>    I am simulating a Copper-TiO2 interface, and since Copper is FCC and TiO2 is tetragonal, I think I need to use ibrav=0. In that case, how do I set up the vacuum around the interface?<br></div>Thanks,<br></div>Sarah<br><br>&CONTROL<br>  calculation='vc-relax',<br>  outdir='.',<br>  prefix='calc',<br>  pseudo_dir = './',<br>  verbosity='high',<br>  tstress=.true.,<br>  tprnfor=.true.,<br>/<br><br>&SYSTEM<br>  ibrav=0,<br>  celldm(1)=20.4938530538d0,<br>  nat=35,<br>  ntyp=3,<br>  ecutwfc=40,<br>  ecutrho=200,<br>  occupations='smearing',<br>  smearing='gaussian',<br>  degauss=0.01<br>/<br><br>&ELECTRONS<br>  diagonalization='david',<br>  conv_thr=1d-08,<br>  mixing_mode='plain',<br>  mixing_beta=0.7,<br>/<br><br>ATOMIC_SPECIES<br>  Cu 63.546000d0 Cu.pw-mt_fhi.UPF<br>  O 15.999400d0  O.pw-mt_fhi.UPF<br>  Ti 47.867000d0 Ti.pw-mt_fhi.UPF<br><br>ATOMIC_POSITIONS {alat}<br>  Cu   0.1666666667d0  -0.1178511302d0   0.1178511302d0<br>...<br><br><br>K_POINTS {automatic}<br>  8 8 8 1 1 1<br><br>CELL_PARAMETERS {alat}<br>  1.000000000000d0  0.000000000000d0  0.000000000000d0<br>  0.000000000000d0  -0.471404520791d0  0.000000000000d0<br>  0.000000000000d0  0.000000000000d0  1.618839606572d0<br><br><br></div>