<div dir="ltr"><div><div><div><div><div><div>Dear All,<br>       <br></div> I am trying to optimize the lattice parameter of <font size="2">Fe<font size="1">2</font>TiSb by running the following code self consistently. But somehow it is giving a lattice parameter of 6.82 Angstrom, which is nowhere near to the lattice parameter I am getting experimentally ( 6.017 Angstrom). <br></font></div><font size="2">My input file is the following,<br><br>    <b> &CONTROL<br>                 calculation = 'scf' ,<br>                restart_mode = 'from_scratch' ,<br>                  wf_collect = .true. ,<br>                      pseudo_dir = './',<br>                outdir='./'<br>                      prefix = 'fta' ,<br>                   verbosity = 'low' ,<br>                     tstress = .false. ,<br>                     tprnfor = .false. ,<br> /<br> &SYSTEM<br>                       ibrav = 2,<br>                   celldm(1) =12.92,<br>                         nat = 4,<br>                        ntyp = 3,<br>                     ecutwfc = 60.0 ,<br>                     ecutrho = 250.0 ,<br>                        nbnd = 30,<br>                 occupations = 'smearing' ,<br>                     degauss = 0.002 ,<br>                    smearing = 'marzari-vanderbilt' ,<br>                       nspin = 2 ,<br>   starting_magnetization(1) = 0.5,<br>   starting_magnetization(2) = 0.6,<br>   starting_magnetization(3) = 0.5,<br> /<br> &ELECTRONS<br>            electron_maxstep = 200,<br>                    conv_thr = 1e-8 ,<br>                 mixing_mode = 'plain' ,<br>                 mixing_beta = 0.3 ,<br>             diagonalization = 'david' ,<br> /<br>ATOMIC_SPECIES<br>   Fe   55.84500  Fe.pbe-mt_fhi.UPF <br>   Ti   47.86700  Ti.pbe-mt_fhi.UPF <br>   Sb  121.76000  Sb.pbe-mt_fhi.UPF <br>ATOMIC_POSITIONS <br>   Fe      0.250000000    0.250000000    0.250000000    <br>   Fe      0.750000000    0.750000000    0.750000000    <br>   Sb      0.000000000    0.000000000    0.000000000    <br>   Ti      0.500000000    0.500000000    0.500000000    <br>K_POINTS {automatic} <br>  2 2 2   0 0 0 <br></b><br><br></font></div><div><font size="2">Where I am changing the celldm(1) in each run.<br></font></div><div><font size="2"><br></font></div><font size="2">Please tell me what am I doing wrong in the calculation.<br><br></font></div><font size="2"> Thanking you in advance,<br> <br></font></div><font size="2">               Sayan Chaudhuri<br></font></div><font size="2">               IIT Indore<br></font></div>