<div dir="ltr"><div>Hi,</div><div><br></div><div>The tutorial works because it is a simple case with small exponents in the basis set. If you have an element (or especially cation) with large exponents in the basis set, you need to use a higher cutoff. The CUTOFF should be at least as large as the largest exponent in your basis set multiplied by the REL_CUTOFF. Then round up to a nice number to report in the paper, nearest 10, 20, 50, or 100 are common. Na, Mg, H, and O are common elements to base your cutoff on.</div><div><br></div><div><div style="background-color: rgb(250, 250, 250); border-color: rgb(187, 187, 187); border-style: solid; border-width: 1px; overflow-wrap: break-word;" class="prettyprint"><code class="prettyprint"><div class="subprettyprint"><span style="color: #606;" class="styled-by-prettify">Na</span><span style="color: #000;" class="styled-by-prettify"> DZVP</span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #000;" class="styled-by-prettify">GTH</span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #000;" class="styled-by-prettify">q9 DZVP</span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #000;" class="styled-by-prettify">GTH<br> </span><span style="color: #066;" class="styled-by-prettify">2</span><span style="color: #000;" class="styled-by-prettify"><br> </span><span style="color: #066;" class="styled-by-prettify">2</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">6</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">3</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">2</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><u><span style="color: #066;" class="styled-by-prettify">17.6698382207</span></u><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #066;" class="styled-by-prettify">0.1362364777</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0270957219</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0791980974</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><span style="color: #066;" class="styled-by-prettify">6.9070658063</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #066;" class="styled-by-prettify">0.0645835666</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0098734119</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.2184139257</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><span style="color: #066;" class="styled-by-prettify">2.6098601451</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.3866153961</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #066;" class="styled-by-prettify">0.0737170396</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.3764887364</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><span style="color: #066;" class="styled-by-prettify">0.9649548796</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.5971358883</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #066;" class="styled-by-prettify">0.2186742776</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.3922304007</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><span style="color: #066;" class="styled-by-prettify">0.3400348369</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.1756697026</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #066;" class="styled-by-prettify">0.0301066303</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.1808407220</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><span style="color: #066;" class="styled-by-prettify">0.0432486046</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #066;" class="styled-by-prettify">0.0017104621</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1.0388865857</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1.0000000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">0.0057696324</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br> </span><span style="color: #066;" class="styled-by-prettify">3</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">2</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">2</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1</span><span style="color: #000;" class="styled-by-prettify"><br>    </span><span style="color: #066;" class="styled-by-prettify">0.0973000000</span><span style="color: #000;" class="styled-by-prettify">  </span><span style="color: #066;" class="styled-by-prettify">1.0000000000</span><span style="color: #000;" class="styled-by-prettify"><br></span></div></code></div></div><div><br></div><div>In my experience, REL_CUTOFF=50 Ry is a good choice for static cell calculations and REL_CUTOFF=80 Ry is a good choice for dynamic cell calculations. Both figures are based on experience with condensed phase simulation. This leads to CUTOFFs of ~600 Ry and ~1000 Ry for liquid water for NVT and NPT simulations, respectively. The devs had a recent paper on accurate simulations of liquid water which draws similar conclusions when not using smoothing.<br></div><div><br></div><div>-T</div><div><br></div><br>On Thursday, October 10, 2019 at 8:13:29 AM UTC-3, Akshay Malik wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr"><div>Dear all,</div><div>I am trying to do cutoff-convergence for my system but it is only converging up to two digits after the decimal point.</div><div>Please suggest some method by which I can get converged energy up to 6 decimals. <br></div><div><br></div><div># Grid cutoff vs total energy</div># Date: Thu Oct 10 16:37:32 IST 2019<br># PWD: /home/space/cp2k/cutoff-<wbr>convergence<br># REL_CUTOFF = 60<br># Cutoff (Ry) | Total Energy (Ha) | NG on grid 1 | NG on grid 2 | NG on grid 3 | NG on grid 4<br>   50.00  -1337.8915343935  668903  50882   240    0<br>  100.00  -1351.0266889654  1216132  286203  11290    0<br>  150.00  -1351.6349634609  1071797  364690  75938   1200<br>  200.00  -1351.6825629692  975942  418150  115933   3600<br>  250.00  -1351.6992612267  875755  439820  192650   5400<br>  300.00  -1351.6990099247  791971  424161  286203  11290<br>  350.00  -1351.6961310939  735698  431201  323555  23171<br>  400.00  -1351.6944391280  687700  428173  341928  55824<br>  450.00  -1351.6933108152  644645  427152  364690  77138<br><div>  500.00  -1351.6931016574  603223  441589  368145  100668</div><div><br></div><div><div>I am using this cp2k file section for calculating energy:</div><div>&FORCE_EVAL<br> METHOD Quickstep<br> &DFT<br>  BASIS_SET_FILE_NAME  GTH_BASIS_SETS<br>  POTENTIAL_FILE_NAME  GTH_POTENTIALS<br>  &MGRID<br>   NGRIDS 4<br>   CUTOFF LT_cutoff<br>   REL_CUTOFF LT_rel_cutoff<br>  &END MGRID<br>  &QS<br>   EPS_DEFAULT 1.0E-10<br>  &END QS<br>  &SCF<br>   SCF_GUESS ATOMIC<br>   EPS_SCF 1.0E-6<br>   MAX_SCF 1<br>   ADDED_MOS 10<br>   CHOLESKY INVERSE<br>   &SMEAR ON<br>    METHOD FERMI_DIRAC<br>    ELECTRONIC_TEMPERATURE [K] 333<br>   &END SMEAR<br>   &DIAGONALIZATION<br>    ALGORITHM STANDARD<br>   &END DIAGONALIZATION<br>   &MIXING<br>    METHOD BROYDEN_MIXING<br>    ALPHA 0.4<br>    BETA 0.5<br>    NBROYDEN 8<br>   &END MIXING<br>  &END SCF<br>   &XC<br>   &XC_FUNCTIONAL BLYP<br>   &END<br>  &END<br> &END DFT</div></div><div><br></div></div>
</blockquote></div>