<div dir="ltr"><div><div><div><div>Dear All,<br></div>            I have optimized the structure for anatase simple tetragonal. The optimiized lattice parameters are a= 3.754336A. c=9.193631522694A. but the experimental values are a= 3.785A, c=9.514A. There is big difference in c value for optimised strucutre.But the same calculation for GGA pseudo potential gives the lattice parameter values which are good with  experimental values. In literature  previous results for LDA has good lattice parameter values.<br> Which parameter I have to  change in order to get good results for LDA? <br>  Below is my input and the version i have used is 5.2.1<br><br> &CONTROL<br>                       title = 'anatase' ,<br>                 calculation = 'vc-relax' ,<br>                restart_mode = 'from_scratch' ,<br>                  pseudo_dir = '/home/suresh/GN2/',<br>                      outdir ='/home/suresh/Desktop/ashahicheck/asahiopt/tmp/',<br>                      prefix = 'anatase' ,<br>                     tstress = .true. ,<br>                     tprnfor = .true. ,<br><br>                 <br>                 <br> /<br> &SYSTEM<br>                       ibrav = 6,<br>                           A = 3.692,<br>                           C = 9.471 ,<br>                         nat = 12,<br>                        ntyp = 2,<br>                     ecutwfc = 60 ,<br>            exxdiv_treatment = 'none' ,<br>                 <br>                    <br>                      <br> /<br> &ELECTRONS<br><br><br> /<br> &IONS<br>                  ion_dynamics = 'bfgs' ,<br>              <br> /<br> &CELL<br>               cell_dynamics = 'bfgs' ,<br><br>               <br> /<br>ATOMIC_SPECIES<br>   Ti   47.86700  Ti.pz-mt_fhi.UPF<br>    O   15.99940  O.pz-mt_fhi.UPF<br>ATOMIC_POSITIONS (crystal)<br>Ti      0.0000000   0.0000000   0.0000000<br>Ti      0.5000000   0.0000000   0.7500000<br>Ti      0.0000000   0.5000000   0.2500000<br>Ti      0.5000000   0.5000000   0.5000000<br>O       0.0000000   0.0000000   0.2066000<br>O       0.5000000   0.0000000   0.5434000<br>O       0.0000000   0.5000000   0.4566000<br>O       0.5000000   0.0000000   0.9566000<br>O       0.0000000   0.5000000   0.0434000<br>O       0.0000000   0.0000000   0.7934000<br>O       0.5000000   0.5000000   0.7066000<br>O       0.5000000   0.5000000   0.2934000<br>K_POINTS automatic <br>4 4 2 1 1 1<br></div><br></div><br></div>Thanks in advance.<br><div><div><div><br><br clear="all"><div><div><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div><div><div style="margin-left:40px;text-align:right">                  With Regards,<br></div><div style="text-align:right">A.Suresh,<br></div></div><div style="text-align:right">Research Scholar,</div></div><div style="text-align:right">Madurai Kamaraj University,<br></div></div><div style="text-align:right">Madurai.<br></div></div></div></div></div></div>
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