Initialization stuck at Shells finder

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Initialization stuck at Shells finder

Postby bob » Tue Sep 21, 2010 10:19 am

Dear all,

while trying yambo on a small molecule toy system, when I try to initialize yambo (yambo -i) the process is stuck at "Shells finder"

Code: Select all
>yambo

 <---> [M 0.015 Gb] Alloc g_vec k_pt dl_sop wf_nc_k wf_igk (0.015)
 __   __  _______  __   __  _______  _______
|  | |  ||   _   ||  |_|  ||  _    ||       |
|  |_|  ||  |_|  ||       || |_|   ||   _   |
|       ||       ||       ||       ||  | |  |
|_     _||       ||       ||  _   | |  |_|  |
  |   |  |   _   || ||_|| || |_|   ||       |
  |___|  |__| |__||_|   |_||_______||_______|

 <---> [01] Job Setup
 <---> [02] Input variables setup
 <---> [02.01] Unit cells
 <---> [02.02] Symmetries
 <---> [02.03] RL shells
 <---> Shells finder |                    | [000%] --(E) --(X)


What can be the reason for that?

Cheers,
Bjoern
Dr. Bjoern Baumeier
Eindhoven University of Technology
Eindhoven, The Netherlands
bob
 
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Re: Initialization stuck at Shells finder

Postby andrea marini » Tue Sep 21, 2010 11:28 am

How many G vectors do you have ? If the number is huge the shell finder may take quite a while to calculate the shells. The easy solution would be then to create an intialization input file with higher verbosity

Code: Select all
> yambo -i -V rl


and reduce the number of G-vectors defined by the variable MaxGvecs
Andrea MARINI
Istituto di Struttura della Materia, CNR, (Italy)
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Re: Initialization stuck at Shells finder

Postby bob » Tue Sep 21, 2010 1:21 pm

I guess it's just a matter of the number of Gvectors, if I read pw.x output correctly:

Code: Select all
     G cutoff =10945.1917  ( 624469 G-vectors)     FFT grid: (216,135, 90)
     G cutoff = 7004.9227  ( 319643 G-vectors)  smooth grid: (180,108, 72)


When I use a very small number of Gvectors in yambo, it works fine. Is there any estimate of how long the Shell finder can take?

Bjoern
Dr. Bjoern Baumeier
Eindhoven University of Technology
Eindhoven, The Netherlands
bob
 
Posts: 42
Joined: Wed Aug 04, 2010 8:39 am
Location: Eindhoven, The Netherlands

Re: Initialization stuck at Shells finder

Postby andrea marini » Thu Sep 23, 2010 3:59 pm

Well. It is not a linear calculation as the number of operations to do increases with the number of shells already found. So I coded the way Yambo estimates the running time only for linear series of steps :? Note however, that, once you calculate the shells those are written in a database that is read in all following calculations. So you may even consider calculating the shells once for all.

To estimate the number of G-vectors needed check the normalization of the wavefunctions. In general you need much less G-vectors than the one in the charge. In your case maybe 10000-50000 could be enough.
Andrea MARINI
Istituto di Struttura della Materia, CNR, (Italy)
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