<div dir="ltr">Dear ... ,<br><br>here is a couple of comments:<br>1) the results are not that bad bearing in mind all approximations made in the PBE functional;<br>2) MOST IMPORTANTLY: one needs to converge the the calculations with respect to k-points. In practice, as you are performing a Gamma-point calculation, you should use a supercell, i.e. replicate your unit cell at least twice in b and c directions. <br>3) Why are you using smearing: is it a metal?<br>4) MOLOPT basis sets are better suited to molecular calculations. Try GTH basis sets.<br>5) GEO_OPT does not optimize the cell at all, that's not an option.<br>6) I don't think you need external pressure as soon as you get a reasonable large cell.<br><br>Yours,<br><br>Vladimir<br><br>четверг, 21 сентября 2017 г., 11:02:59 UTC+2 пользователь ganta....@gmail.com написал:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Hi all,<div><br></div><div>I am trying to do cell optimization of a goethite FeOOH unit cell. The lattice parameters of the considered unit cell are a=9.91340 b=3.0128, c=4.58 ( the same values I used in cp2k).</div><div><br></div><div>I have tested all three cases (direct cell opt, geo opt, MD) of the CELL_OPT and </div><div><br></div><div>The cell optimized values are approximately a=9.33, b=3.063 c=4.179. </div><div><b>The experiment values of lattice constants are a=9.96 b=3.02 c=4.62. </b><br></div><div><b><br></b></div><div><b>I want to obtain the optimized values close to expt. values. </b></div><div><b><br></b></div><div>In trail and error, I have used STESS_TENSOR NUMERICAL, I have disabled D3 correction and I have also used zero pressure. </div><div><br></div><div><br></div><div><br></div><div>Below is my input file. </div><div><div>&Global </div><div> PROJECT goethite_cellopt </div><div> RUN_TYPE CELL_OPT </div><div> PRINT_LEVEL LOW </div><div>&END GLOBAL </div><div> </div><div>&FORCE_EVAL </div><div> METHOD Quickstep </div><div> STRESS_TENSOR ANALYTICAL </div><div> &DFT </div><div> BASIS_SET_FILE_NAME BASIS_MOLOPT </div><div> POTENTIAL_FILE_NAME GTH_POTENTIALS </div><div> CHARGE 0 </div><div> MULTIPLICITY 1 </div><div> &MGRID </div><div> NGRIDS 5 </div><div> CUTOFF 600 </div><div> REL_CUTOFF 60 </div><div> &END </div><div> &QS </div><div> METHOD GPW </div><div> EPS_DEFAULT 1.0E-12 </div><div> EXTRAPOLATION ASPC </div><div> EXTRAPOLATION_ORDER 4 </div><div> &END </div><div> &SCF </div><div> SCF_GUESS ATOMIC </div><div> MAX_SCF 1500 </div></div><div><div> EPS_SCF 1.0E-8 </div><div> &OUTER_SCF </div><div> MAX_SCF 30 </div><div> EPS_SCF 1.0E-8 </div><div> &END </div><div> ADDED_MOS 30 </div><div> CHOLESKY INVERSE </div><div> &SMEAR ON </div><div> METHOD FERMI_DIRAC </div><div> ELECTRONIC_TEMPERATURE [K] 300 </div><div> &END SMEAR </div><div> &DIAGONALIZATION </div><div> ALGORITHM STANDARD </div><div> &END DIAGONALIZATION </div><div> &MIXING </div><div> METHOD BROYDEN_MIXING </div><div> ALPHA 0.1 </div><div> BETA 1.5 </div><div> NBROYDEN 8 </div><div> &END MIXING </div><div> &END SCF </div><div> &XC </div><div> &XC_FUNCTIONAL PBE </div><div> &END XC_FUNCTIONAL </div><div> &VDW_POTENTIAL </div><div> POTENTIAL_TYPE PAIR_POTENTIAL </div><div> &PAIR_POTENTIAL </div><div> PARAMETER_FILE_NAME dftd3.dat </div><div> TYPE DFTD3 </div><div> REFERENCE_FUNCTIONAL PBE </div><div> R_CUTOFF [angstrom] 15 </div><div> &END </div><div> &END VDW_POTENTIAL </div><div> &END XC </div><div> &END DFT </div><div> </div><div> &SUBSYS </div><div> &CELL </div><div> ABC [angstrom] 9.91340 3.01280 4.58000 </div><div> PERIODIC XYZ </div><div> &END CELL </div><div> &TOPOLOGY </div><div> COORD_FILE_NAME <a href="http://goethite_unitcell.xyz" target="_blank" rel="nofollow" onmousedown="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2Fgoethite_unitcell.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNHyVwbPplZol9XkxYoz8XQOlk7gJw';return true;" onclick="this.href='http://www.google.com/url?q\x3dhttp%3A%2F%2Fgoethite_unitcell.xyz\x26sa\x3dD\x26sntz\x3d1\x26usg\x3dAFQjCNHyVwbPplZol9XkxYoz8XQOlk7gJw';return true;">goethite_unitcell.xyz</a> </div><div> COORD_FILE_FORMAT XYZ </div><div> &CENTER_COORDINATES T </div><div> &END CENTER_COORDINATES </div><div> &END </div><div> &KIND H </div><div> BASIS_SET DZVP-MOLOPT-SR-GTH </div><div> POTENTIAL GTH-PBE-q1 </div><div> &END KIND &KIND Fe </div><div> BASIS_SET DZVP-MOLOPT-SR-GTH </div><div> POTENTIAL GTH-PBE-q16 </div><div> &END KIND </div><div> &KIND O </div><div> BASIS_SET DZVP-MOLOPT-SR-GTH </div><div> POTENTIAL GTH-PBE-q6 </div><div> &END KIND </div><div> <br></div><div> &END SUBSYS </div><div>&END FORCE_EVAL </div><div> </div><div>&MOTION </div><div> &CELL_OPT </div><div> OPTIMIZER BFGS </div><div> MAX_ITER 5000 </div><div> KEEP_ANGLES T </div><div> EXTERNAL_PRESSURE 1.01325 0 0 0 1.01325 0 0 0 1.01325 </div><div> &END </div><div>&END </div><div><br></div><div><br></div><div>Goethite unit cell</div><div><br></div><div>16 <br></div><div>Fe H O2 </div><div>Fe 1.446365 0.753200 4.357412 </div><div>Fe 8.467034 2.259600 0.222588 </div><div>Fe 3.510335 2.259600 2.067412 </div><div>Fe 6.403065 0.753200 2.512588 </div><div> H 8.912147 0.753200 2.752580 </div><div> H 1.001253 2.259600 1.827420 </div><div> H 5.957953 2.259600 0.462580 </div><div> H 3.955446 0.753200 4.117420 </div><div> O 7.940633 0.753200 1.305300 </div><div> O 1.972767 2.259600 3.274700 </div><div> O 6.929466 2.259600 3.595300 </div><div> O 2.983933 0.753200 0.984700 </div><div> O 9.400877 0.753200 3.682320 </div><div> O 0.512523 2.259600 0.897680 </div><div> O 5.469223 2.259600 1.392320 </div><div> O 4.444177 0.753200 3.187680 </div><div><br></div><div><br></div><div>Please let me know if you have any suggestions. </div><div> </div><div> </div></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div></div></blockquote></div>