<div dir="ltr">Hello Aditya,<div><br></div><div>It is not clear what basis set you are using, since there are two DZVP-MOLOPT-SR-GTH for Ce, one with 12 electrons (-q12) and another with 30 electrons (-q30).</div><div>In my experience the best approach to know a cutoff estimate is from the HIGHER_COEFFICIENT in the whole basis set. Taking the result from HIGHER_COEFFICIENT*REL_CUTOFF you can get an approximate CUTOFF for convergence.</div><div>From BASIS_MOLOPT_UCL file, the DZVP-MOLOPT-SR-GTH-q12 basis set has a HIGHER_COEFFICIENT of 4.348 and DZVP-MOLOPT-SR-GTH-q30 basis set has a HIGHER_COEFFICIENT of 18.922, so with a REL_CUTOFF of 60Ry, the convergence must be reached at 260Ry and 1135Ry respectively.</div><div>Also, if you are using smoothers (XC_GRID section), the convergence test behavior will not be as expected, with a monotonous convergence... in my experience always show more oscillations...</div><div>A last thing, the EPS_DEFAULT and EPS_SCF values are important to reach a good CUTOFF convergence, values of 1E-12 and 1E-06, respectively, are usually good.</div><div><br></div><div>Regards - Lucas</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">El mar, 11 abr 2023 a las 3:33, Aditya Goyal (<<a href="mailto:goyal.aditya74@gmail.com">goyal.aditya74@gmail.com</a>>) escribió:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Dear CP2K users,<div>I'm trying to simulate a molten cerium chloride system with 40CeCl3 molecules. Before performing any extensive calculation, I'm trying to benchmark the cutoff energy used in the DFT section by performing single-point energy calculations. I'm using DZVP basis sets for Ce & Cl with PBE functional by taking 800 Ry as a benchmark for comparison. </div><div><br></div><div>For a Relative cutoff of 60 Ry </div><div>Cutoff Energy(Ha) Delta E (kJ/mol) wrt. 800 Ry</div><div>350 Ry <span style="white-space:pre-wrap"> </span>-3357.32389476218<span style="white-space:pre-wrap"> </span> 3.61119311934135<br>550 Ry <span style="white-space:pre-wrap"> </span>-3357.3063307436<span style="white-space:pre-wrap"> </span> 49.7255239006927<br>600 Ry <span style="white-space:pre-wrap"> </span>-3357.27607335904<span style="white-space:pre-wrap"> </span> 129.166287063426<br>650 Ry <span style="white-space:pre-wrap"> </span>-3357.28237568966<span style="white-space:pre-wrap"> </span> 112.619518020088<br>700 Ry <span style="white-space:pre-wrap"> </span>-3357.31280473755<span style="white-space:pre-wrap"> </span> 32.7280527853891<br>750 Ry <span style="white-space:pre-wrap"> </span>-3357.31982535559<span style="white-space:pre-wrap"> </span> 14.2954201205428<br>800 Ry <span style="white-space:pre-wrap"> </span>-3357.32527019281<span style="white-space:pre-wrap"> </span> 0.00000000000000<br></div><div><br></div><div>Similarly, For a Relative cutoff of 100 Ry</div><div>Cutoff Energy(Ha) Delta E (kJ/mol) wrt. 800 Ry<br></div><div>350 Ry <span style="white-space:pre-wrap"> </span>-3357.31559413633<span style="white-space:pre-wrap"> </span> -49.9141589061937<br>550 Ry <span style="white-space:pre-wrap"> </span>-3357.3107413093<span style="white-space:pre-wrap"> </span> -37.1730615379035<br>600 Ry <span style="white-space:pre-wrap"> </span>-3357.29750596273<span style="white-space:pre-wrap"> </span> -2.42365911922866<br>650 Ry <span style="white-space:pre-wrap"> </span>-3357.33819509308<span style="white-space:pre-wrap"> </span> -109.252970852155<br>700 Ry <span style="white-space:pre-wrap"> </span>-3357.32224091494<span style="white-space:pre-wrap"> </span> -67.3652761456795<br>750 Ry <span style="white-space:pre-wrap"> </span>-3357.30040482541<span style="white-space:pre-wrap"> </span> -10.0346230856023<br>800 Ry <span style="white-space:pre-wrap"> </span>-3357.29658283985<span style="white-space:pre-wrap"> </span> 0.00000000000000<br></div><div><br></div><div>So, I'm not finding a convergence of energy or any particular trend at any cutoff (for both relative cutoff cases). Can anyone suggest some parameter changes that may be used to achieve convergence? Any help would be appreciated. </div><div><br></div><div>Regards</div><div>Aditya</div><div><br></div><div><br></div><div><br></div>
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