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<font size="-1">Dear Dennis,<br>
<br>
the SURF program works the following way: let us consider the 3D
surfaces as these are usually the surfaces where the trouble
starts. The 3D surface generation consists of 2 important steps,
a) the point generation step and b) the convergence step. In the
first iteration in a) 2^3 ab initio points (2 points per
direction) will be computed for each individual 3D subsurface
(mode-coupling term). Let us assume you have 100 of such surfaces,
then 800 points will be computed within the first iteration. Once
this task has been completed, the individual surfaces will be
tested, if they are converged or not (this is step b). There are
several criteria to be met. Let us now assume, 10 of the 100
surfaces are already converged. In that case, these 10 surfaces
will be dumped to disk, while for the other 90 surfaces (4^3-2^3)
ab initio points will be added by going back to step a). Once that
task has been finished, the program checks again on convergence.
Again, some surfaces will be converged and these will be dumped to
disk. As most surfaces will be converged after 3-5 iterations,
this is the number of times, surfaces will be dumped to disk for
restarting. I hope this answers your question I).<br>
<br>
Now to question II). Let us assume you have a molecule with 12
atoms. In that case you have 30 degrees of freedom and thus
30*29*28/6=4060 3D terms (subsurfaces) in the multimode expansion.
This is called the list of 3D terms and its has nothing to do with
grid points. This list will be divided into batches. If you are
running the job on just one core, each batch consists of 30 3D
terms, i.e. 236 batches will be produced. As outline above, each
batch again has about 3-5 restart points or iterations, Note, all
this has nothing to do with grid points. Now let's have a look at
your calculation. You mentioned, you are using 32 cores, which
means that the first batch consists of 30*32=960 3D terms (or
subsurfaces). If we assume that on average each 3D terms needs 216
grid points (6 points per dimension in C1 symmetry), the first
batch, which will consist of 3-5 iterations, contains about 207360
grid points. Probably you should set BATCH3D to 1 or 2 (only
integers are allowed). <br>
<br>
I hope this sheds some light into the dark.<br>
<br>
Guntram<br>
<br>
</font><br>
<div class="moz-cite-prefix">On 10/20/17 13:23, Dinu, Dennis Florian
wrote:<br>
</div>
<blockquote
cite="mid:03DF623C9A80794AADC9AE820307C12669E07F08@XMBX2.uibk.ac.at"
type="cite">
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<div style="direction: ltr;font-family: Tahoma;color:
#000000;font-size: 10pt;">Dear Molpro Community,
<div><br>
</div>
<div>I am trying to calculate a quite large PES, by using a HPC
with a walltime of 10 days. That means, i have to control the
SURF Program somehow, to dump parts of the PES within this
walltime. Now I need some help in understanding the BATCH3D
option of the SURF Program. It says:</div>
<div><br>
<div>------------------------------------------------------------------------------------------</div>
<div>After calculating a number of grid points within the
iterative interpolation</div>
<div>scheme the convergence of the individual surfaces will be</div>
<div>checked and, if provided by the keyword DUMP, dumped to
disk.</div>
<div><b>This leads typically to 3-5 iterations and thus the
same number of</b></div>
<div><b>restart points within the calculation of the 1D, 2D,
... surfaces (I)</b>. As</div>
<div>the number of 3D and 4D terms can be very large this is
not sufficient</div>
<div>in these cases. <b>Therefore, the lists of 3D and 4D
terms is cut</b></div>
<div><b>into batches which will be processed subsequently
(II).</b> BATCH3D and</div>
<div>BATCH4D control the number of 3D and 4D surfaces within
each</div>
<div>batch. By default BATCH3D is set to 30 times the number
of processors</div>
<div>and BATCH4D to 10 times the number of processors.
Accordingly</div>
<div>the number of restart points is increased. Smaller values
for</div>
<div>BATCH3D and BATCH4D, e.g. BATCH3D=20, increase the number</div>
<div>of restart points on cost of the efficiency of the
parallelization.</div>
</div>
<div>------------------------------------------------------------------------------------------</div>
<div><br>
</div>
<div><b>(I)</b> Why does this lead to 3-5 Iterations?</div>
<div><br>
</div>
<div><b>(II) </b>What is a List? Is it a list of Grid-Points,
or a list of full 3D sub-potentials? Or something else?</div>
<div><br>
</div>
<div>I am trying to figure out the correct BATCH3D settings for
my needs. <br>
When I do <br>
<span style="white-space:pre"></span>grep "MODE" *log* | wc </div>
<div>I get the number of Grid-points. In my case after 10 days
calculation on 32 processors -> 24494</div>
<div>With the default BATCH3D=30, the DUMP should happen after
30*32=960 Grid-points. As this did not happen, my next quess
is that the DUMP happens after 960 3D sub-potentials.
<br>
That means <span style="font-size: 13.3333px;">when one 3D
sub-potential comprises 16*16*16 = 4096 grid-points (</span><span
style="font-size: 10pt;">roughly spoken with NGRID=16 and
ignoring symmetry and prescreening), then i have just 6 3D
sub-potentials within 10 days. That means I would have to
set BATCH3D=0.2, to have DUMP after 0.2*32=6.4 3D
sub-potentials. Does this make any sense to you?</span></div>
<div><span style="font-size: 10pt;"><br>
</span></div>
<div><span style="font-size: 10pt;">greets <br>
Dennis</span></div>
<div><br>
<br>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
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<pre class="moz-signature" cols="72">--
********************************************************************************
Apl. Prof. Dr. Guntram Rauhut
Institut f. Theoretische Chemie
Universitaet Stuttgart
Pfaffenwaldring 55
D-70569 Stuttgart
Germany
Tel. : +49/(0)711/685-64405
FAX : +49/(0)711/685-64442
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