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Dear Tatiana,<br>
<br>
Many thanks for your response. While struggling with the problem I
increased the integral accuracy (to 1dE-20) as well as<br>
the accuracy for the T1+T2 amplitudes (to 1dE-12) . However, this
did not help. Concerning the Davidson, the default<br>
20 vectors per state should be OK because the problematic state is
actually the lowest one. It is in fact a doubly degenerate (E')<br>
state, that is there are two states of A' (the molecule has C3h
symmetry, the computational group is Cs).<br>
I do not think the problem relates to degeneracy, as other,
higher-lying degenerate states converge smoothly.<br>
The problem occurs only at the EOM-CCSD level, at ADC(2) everything
is fine. I also tried EOM in CFOUR and it is<br>
the same. I am stumped with what can be wrong with that state.<br>
I wonder what one could look at (print out) to trace the problem
back?<br>
<br>
Best regards,<br>
Evgeniy<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 06/07/2017 05:20 PM, Tatiana Korona
wrote:<br>
</div>
<blockquote
cite="mid:Pine.LNX.4.64.1706071709001.1950@tiger.chem.uw.edu.pl"
type="cite">Dear Evgeniy, <br>
<br>
This message can signify near-linear dependencies in the small
space in the Davidson procedure. One can try to a) increase the
quality of the integrals (for the case when this dependence is
caused by numerical noise of orbitals and CCSD amplitudes - note
that if CCSD is not a final step, a bit more accurate T1+T2
amplitudes are often required); b) try to play with Davidson
options, e.g. change MAXDAV. <br>
<br>
Another issue is a high energy of the virtual orbital. I presume
you want to obtain some high-lying states, what often means that
there is a large density of states having a significant component
of the excitation to this orbital and then the procedure will jump
from one state to another and back (or to yet another state). In
this case sometimes it helps if you ask for more states (but only
sometimes). In general finding high states is a difficult
no-black-box task, unfortunately :-( <br>
<br>
Best wishes, <br>
<br>
Tatiana <br>
<br>
On Tue, 6 Jun 2017, Evgeniy Gromov wrote: <br>
<br>
<blockquote type="cite">Hello, <br>
<br>
I encountered some unclear problem when doing EOM-CCSD
calculations <br>
for an Ir complex. All steps till EOM went fine, but in EOM I
get the <br>
following warning: <br>
<br>
The smallest eigenvalue of S-eff matrix 0.8656157915E-13 <br>
This can lead to convergence problems! <br>
<br>
and two of the five roots do not seem to have converged; there
is <br>
no "Converged" message for them after 50 iterations. <br>
<br>
I wonder what this could be caused by? Could it be due to a very
high <br>
in energy (63.5 hartree) virtual orbital? <br>
<br>
Best regards, <br>
Evgeniy <br>
<br>
-- <br>
Dr. Evgeniy Gromov <br>
Theoretische Chemie <br>
Physikalisch-Chemisches Institut <br>
Im Neuenheimer Feld 229 <br>
D-69120 Heidelberg <br>
Germany <br>
<br>
Telefon: +49/(0)6221/545213 <br>
Fax: +49/(0)6221/545221 <br>
E-mail: <a class="moz-txt-link-abbreviated"
href="mailto:evgeniy.gromov@pci.uni-heidelberg.de">evgeniy.gromov@pci.uni-heidelberg.de</a>
<br>
<br>
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href="http://www.molpro.net/mailman/listinfo/molpro-user">http://www.molpro.net/mailman/listinfo/molpro-user</a>
<br>
<br>
</blockquote>
<br>
Dr. Tatiana Korona <a class="moz-txt-link-freetext"
href="http://tiger.chem.uw.edu.pl/staff/tania/index.html">http://tiger.chem.uw.edu.pl/staff/tania/index.html</a>
<br>
Quantum Chemistry Laboratory, University of Warsaw, Pasteura 1,
PL-02-093 Warsaw, POLAND <br>
<br>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Dr. Evgeniy Gromov
Theoretische Chemie
Physikalisch-Chemisches Institut
Im Neuenheimer Feld 229
D-69120 Heidelberg
Germany
Telefon: +49/(0)6221/545213
Fax: +49/(0)6221/545221
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:evgeniy.gromov@pci.uni-heidelberg.de">evgeniy.gromov@pci.uni-heidelberg.de</a></pre>
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