<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Dear Johannes,<div class=""><br class=""></div><div class="">I don’t know if I’ve well understood your point or if I’m missing something. However, after looking yo the plots you posted on Google Drive, it seems to me that actually your forces are fully converged even at the smallest values of ecutrho.</div><div class="">For example, in S.tif, I see the scale ranging from 0.130328 to 0.130340 Ry/a.u., about 1.e-5 wide. Similarly, just to consider another case, in O5.tif forces range from 0.45811 to 0.45815, about 4.e-5 wide (and if you discard the first point the range is reduced by a further factor of 10).</div><div class=""><br class=""></div><div class="">Now, the default value for convergence of forces is 1.e-3 a.u., see <a href="https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm119" class="">https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm119</a></div><div class=""><br class=""></div><div class="">So, this means that your forces are much more converged than the threshold used by QE, unless you otherwise specified in your input.</div><div class=""><br class=""></div><div class="">You can also see some sample convergence plots on forces here:</div><div class=""><a href="http://theossrv1.epfl.ch/Main/ElectronicTemperature" class="">http://theossrv1.epfl.ch/Main/ElectronicTemperature</a></div><div class="">The vertical axis spans a range of about 0.2 eV / A ~ 0.2 / 25.7 Ry / Bohr ~ 0.008 Ry / Bohr, again ~2-3 orders of magnitude larger that the same range in your plots.</div><div class=""><br class=""></div><div class="">Giovanni</div><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 1 Mar 2022, at 19:00, Johannes Meusburger - STFC UKRI via users <<a href="mailto:users@lists.quantum-espresso.org" class="">users@lists.quantum-espresso.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta charset="UTF-8" class=""><div style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;" class=""><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class="">Dear all,<o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class="">I have observed a rather curious behaviour when performing convergence testing for CuSO4 x 5H2O. For the convergence testing I have displaced the oxygens surrounding the Cu and S atom by 10% of the equilibrium Cu-O and S-O bond lengths and computed the forces on each of the atoms for various k-point grids, smearing widths (marzari-vanderbilt type), ecutrho and ecutwfc. To my surprise I found that the ecutrho value did not converge up to a dual parameter of 5 (i.e., wfc cut = 50 Ry and ecutrho = 1000 Ry; forces vs dual parameter plots available on google drive:<a href="https://drive.google.com/drive/folders/1YaotezLaEHiSKouW19azGMdC6T8J-Jg8?usp=sharing" class="">https://drive.google.com/drive/folders/1YaotezLaEHiSKouW19azGMdC6T8J-Jg8?usp=sharing</a>).<o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class=""><span class=""> </span>I am using ultrasoft PP from the GBRV library, usually I find that a dual parameter of 2 or 3 (i.e., ecutrho 8 or 12 times larger than ecutwfc) yields well converged forces. My question now is if there is any reason, why I should NOT use such a high dual parameter for the geometry optimization?<o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class="">All the best and many thanks,<o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class="">Johannes<o:p class=""> </o:p></span></div><div style="border-style: none none solid; border-bottom-width: 1.5pt; border-bottom-color: windowtext; padding: 0cm 0cm 1pt;" class=""><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif; border: none; padding: 0cm;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class="">Johannes Meusburger<span class="Apple-converted-space"> </span><o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class="">ISIS Neutron and Muon Source, UK<o:p class=""> </o:p></span></div><div style="margin: 0cm; text-align: justify; line-height: 24px; font-size: 12pt; font-family: "Times New Roman", serif;" class=""><span lang="EN-US" class=""><o:p class=""> </o:p></span></div><br class=""></div><div style="margin-top: 0px; margin-bottom: 0px; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 18px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="font-size: 6pt;" class="">This email and any attachments are intended solely for the use of the named recipients. 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