<div dir="ltr">Dear Q-E users<div>I m trying to get the band gap for System Cu2SnS3 with DFT + U. </div><div>I have done calculation PBE + U by Considering U = 4, 5 , 6 , 7, 9  upto 15 and with increasing U values, band gap for the system also  increases. </div><div>Is there any specific limit for consideration of U value ?</div><div><br></div><div><br></div><div>Input file</div><div>-----------------------------------------------------------------------------------</div><div>&CONTROL<br>                       title = 'CTS'<br>                 calculation = 'scf'<br>                restart_mode = 'from_scratch'<br>                      outdir = './scratch'<br>                  pseudo_dir = './'<br>                      prefix = 'CTS'<br>                   verbosity = 'high'<br>                       nstep = 1000<br>/<br>&SYSTEM<br>                       ibrav = 0<br>                         nat = 12<br>                        ntyp = 3<br>                     ecutwfc = 80<br>                     ecutrho = 640<br>              lda_plus_u = .TRUE.<br>             lda_plus_u_kind = 0<br>            Hubbard_U(1) = 15<br>/<br>&ELECTRONS<br>            electron_maxstep = 100<br>                 mixing_mode = 'plain'<br>                 mixing_beta = 0.4<br>                 mixing_ndim = 8<br>             diagonalization = 'cg'<br>/<br>&IONS<br>                ion_dynamics = 'bfgs'<br>/<br>&CELL<br>               cell_dynamics = 'bfgs'<br>/<br>ATOMIC_SPECIES<br>   Cu   63.5460000000  Cu.pbe-dn-kjpaw_psl.1.0.0.UPF<br>   Sn  118.7100000000  Sn.pbe-dn-kjpaw_psl.1.0.0.UPF<br>    S   32.0650000000  S.pbe-n-kjpaw_psl.1.0.0.UPF<br><br>ATOMIC_POSITIONS {crystal}<br>Cu       0.609860025   0.554603242   0.014502826<br>Cu       0.756853280   0.738042423   0.513837567<br>Cu       0.445393448   0.390139697   0.514502899<br>Cu       0.261956405   0.243147538   0.013839616<br>Sn       0.090842876   0.093003410   0.494452226<br>Sn       0.906995789   0.909160925   0.994450414<br>S        0.060036047   0.768130605   0.387963060<br>S        0.231871856   0.939963608   0.887965000<br>S        0.886684205   0.601038738   0.879478677<br>S        0.398964467   0.113313382   0.379479276<br>S        0.537436346   0.292294346   0.880764475<br>S        0.707707256   0.462560085   0.380765964<br><br>K_POINTS {automatic}<br>5 5 5  0 0 0<br></div><div>CELL_PARAMETERS {bohr}<br>  12.820803911   0.000373966   0.017355449<br>   6.411463480  11.102558326  -0.017368345<br>  -2.152496468   3.728515202  12.101963487<br></div><div>----------------------------------------------------------------------------------------------------------</div><div><br></div><div><br></div><div>Regards </div><div>Rohit Dahule</div><div><div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>Rohit Dahule</div><div>M. Tech. Student<br></div><div>Materials Science and Engineering</div><div>IIT Gandhinagar<br></div></div></div></div></div></div></div></div></div></div>