[Pw_forum] a question about a calculation on a relatively large system

[Peter Winey]

Dear all,

I am trying to do a structural relaxation on a relatively large system,
which
has 240 atoms in one unit cell.

I know it may sound crazy, but the crystal contains only C and H atoms,
so I thought that my cluster might be able to handle it.

Indeed, I was able to run pwscf structural relaxation calculations. The 1st
iteration finished ok. However, at the end of the 2nd iteration (which also
finished ok), after the program printed out:
------------------------------------------
...
number of scf cycles = 2
number of bfgs steps = 1
energy old =  - 2084.xxx
energy new = - 2086.xxx
CASE: energy_new < energy_old
------------------------------------------
The run stopped without giving any information expect saying that "mpi
stopped without calling mpi_finalize" or sth like that.

I repeated the calculation and it always stopped at the same place.
It is wierd since I had no problem before when running smaller systems
(say, 150 atoms).

Could some one give me a hint on what could be the reason? Is it related
to the system size? If so, I have no idea why the pw.x program is able to
finish the first and the second iteration, but does not continue...

Thanks in advance for any suggestions that you may have!

-Peter

********************************************
Peter Winey, Ph.D., DuPont
peterwiney at gmail.com
********************************************
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