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Dear all, </div>
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I appreciate this topic has been discussed a number of times in the forum, with the answer that all components of all forces should satisfy the forc_conv_thr. This leads me to my probably very simple query that likely stems from a misunderstanding. </div>
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when I run a vc-relax calculation with e.g. a very tight forc_conv_thr=<span style="background-color: rgb(255, 255, 0);">1.0D-5</span>, my calculation finishes 'successfully' with e.g.:</div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> </span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 1 type 3 force = 0.00000250 0.00000250 0.00000250</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 2 type 3 force = 0.00000432 0.00000559 0.00000432</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 3 type 3 force = 0.00000432 0.00000432 0.00000559</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 4 type 3 force = 0.00000559 0.00000432 0.00000432</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 5 type 2 force = -0.00000391 0.00000100 0.00000100</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 6 type 2 force = 0.00000361 -</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);">0.00001336
</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">-0.00001336</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 7 type 2 force = 0.00000100 -0.00000391 0.00000100</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 8 type 2 force = 0.00000100 0.00000100 -0.00000391</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 9 type 2 force = </span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);"> -0.00001336</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
-</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);">0.00001336 </span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">0.00000361</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 10 type 2 force = </span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);"> -0.00001336</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">
0.00000361 -</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);">0.00001336</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">even if I put rather ridiculous thresholds of forc_conv_thr=1.0D-7 it makes no real
difference to the force components:</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 1 type 3 force = -0.00000456 -0.00000456 -0.00000456</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 2 type 3 force = 0.00000832 </span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);">0.00001867
</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">0.00000832</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 3 type 3 force = 0.00000832 0.00000832 0.00001867</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 4 type 3 force =
</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);">0.00001867 </span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">0.00000832
0.00000832</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 5 type 2 force = -0.00000414 -0.00000409 -0.00000409</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"> atom 6 type 2 force = -0.00000040 -</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgb(255, 255, 0);">0.00004042
</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">-0.00004042</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">If I understand the output correctly, it appears as though some force components have
converged fine, though quite a few components have not reached the threshold, and changing the threshold makes little difference. As we do a lot of work on vibrational dynamics in dispersion bound crystals, tight forces are usually quite important. We've recently
moved into using QE and I'm trying to get to grips with how to control the forces in QE optimisations but am clearly missing something. Could anybody please point me in the right direction? </span></div>
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</span></div>
<div style="direction: ltr;"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);">Many thanks in advance,</span></div>
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<span style="color: rgb(67, 67, 67);"> Adam Michalchuk </span></div>
<p style="margin: 0cm; font-family: Calibri, sans-serif; font-size: 11pt;"><span style="color: rgb(64, 64, 64);">University of Birmingham UK</span></p>
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