<p dir="ltr">Dear Matt (and Marcella who basically replied the same in private),</p>
<p dir="ltr"> Thanks a million, using the molopt basis set does fix things. I had tried both the dzvp from basis_sets and gth_basis_set, and I was getting similar nonsense.</p>
<p dir="ltr">I am a bit scared seeing how much difference it makes changing the basis set. Any idea why graphite should be such a nasty beast? I had experimented with different basis sets for water and never saw such a dramatic effect.</p>
<p dir="ltr">All the best,<br>
Michele</p>
<div class="gmail_quote">On 28 May 2014 19:23, "Matt W" <<a href="mailto:MattWa...@gmail.com">MattWa...@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi Michele,<div><br></div><div>please try using the MOLOPT basis sets provided with CP2K ($CP2K_root/tests/QS/BASIS_MOLOPT) that prehaps give a more suitable starting point for describing a "molecular" system like graphite than atomic optimization based ones.</div>
<div><br></div><div>Using a DZVP-MOLOPT-SR-GTH basis - I get SCF convergence in ~10 cycles and geometry converges in ~10 steps (with BFGS).</div><div><br></div><div>Matt<br><br>On Wednesday, May 28, 2014 5:19:30 PM UTC+1, Michele Ceriotti wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex">
<p dir="ltr">Hi Matthias, <br>
Thanks for the quick answer. I have already played with the obvious parameters, point is it is impossible to converge the scf properly. <br>
Everything looks like what you get when the geometry is crazy, and indeed my student tried to enlarge the cell (by almost 10%!) and got converged scf and more reasonable forces. <br>
However this is inconsistent with the literature and the results from siesta.<br>
We have been trying to fiddle with the scf parameters for days, but get consistently 100au forces on a geometry that should be very close to optimum.<br>
Do you see something wrong with how we define the cell or the positions?<br>
Best<br>
Michele</p>
<div class="gmail_quote">On 28 May 2014 17:47, "Matthias Krack" <<a>matth...@psi.ch</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi Michele,<br><br>I would suggest to set EPS_DEFAULT in @QS section at least to 1.0E-12 or lower and for the ALPHA in &MIXING I would also use a smaller value like 0.2. Maybe this will help to converge your system properly.<br>
<br>Matthias<br><br>On Wednesday, May 28, 2014 4:20:44 PM UTC+2, Michele Ceriotti wrote:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear CP2K community, <br>
<br> I have been trying for a few days to set up calculations of graphite as an exercise for a student but I am getting the weirdest results. I am sure in the it will end up being a silly mistake in the input, but I can't get to see it so perhaps someone can help. <br>
<br>Despite using a fairly large FD smearing, the SCF cycle has a hard time converging, and when the maximum number of steps is reached <br><br> 50 Broy./Diag. 0.50E+00 1.2 0.00014351 -819.2909959720 -2.28E-09<br>
*** SCF run NOT converged ***<br><br>and the calculation carries on with what it has got, diagnostics are really strange. <br><br>For a start, eigenvalues show two weird very low-energy states<br> MO EIGENVALUES AND MO OCCUPATION NUMBERS<br>
# MO index MO eigenvalue [a.u.] MO occupation<br> 1 -21.523076 2.000000<br> 2 -21.517160 2.000000<br> 3 -1.383548 2.000000<br>
4 -0.510418 2.000000<br><br>forces on the atoms are insane<br> ATOMIC FORCES in [a.u.]<br> # Atom Kind Element X Y Z<br> 1 1 C 4.68736611 4.63921800 -222.86999309<br>
2 1 C -1.57720920 -4.48651652 124.33822840<br> 3 1 C -5.01734639 3.10518104 176.16292919<br><br>and so is the stress tensor<br> STRESS TENSOR [GPa]<br> X Y Z<br>
X -8233.84728056 8.05482610 0.90481573<br> Y 8.05482610 -9552.76932222 -0.49445437<br> Z 0.90481573 -0.49445437 -2526.59040628<br><br>I was thinking of an error in the structure or the cell parameters, but I checked it many times and everything seems in order. The same structure, with same functional and similar parameters in SIESTA converges like a stone, and gives no problem whatsoever. <br>
<br>Can you spot something obvious that I am missing? I'd really like to use CP2K for this exercise, but I can't seem to figure out what is going wrong. <br><br>Many thanks,<br>Michele<br><br></div></blockquote>
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