Dear all,
I have found convergence problems in geometry optimization runs with both Abinit7.6.2 and Abinit7.10.2, when running in parallel, for several different systems (isolated molecule; adsorbed molecules on a silicon slab with several different cells, molecule type, and adsorption configurations), on the CINECA cluster Galileo (http://www.hpc.cineca.it/hardware/galileo).
After a number of “correct” geometry optimization steps with total energy and "max grad (force/stress)" decreasing (usually 6 to 8 steps for the case I am attaching: molecules adsorbed on a silicon slab, 4x2 cell), the selfconsistency starts failing to converge in a reasonable number of steps; then, in the following geom. opt. iterations, the "max grad (force/stress)" and the total energy increase, and after few steps the geometry of my system “explodes” (bonds break etc).
If performing a geom. opt. run starting from the last “correct” geom. opt. iteration of a previous one as defined above, also the new calculation will run with the correct behaviour for 6 to 8 iterations (i.e. beyond the “critical iteration” where the previous one failed), before starting to show the same problems as mentioned above. This procedure can be iterated, yielding reasonable behaviour of total energies and of system geometries. The system is nonmetallic, and anyway the same problem is found both with or without using metallic occupations (occopt 3) and a smearing.
No problems were found, instead, on selfconsistent calculations on given (reasonable) geometries of the same system, neither in band structure calculations.
In those cases (small gas phase molecule) where it was feasible to perform a serial run on the same machine, or a parallel run on our local linux cluster, the geom. opt. calculations converged regularly. Also, I never encountered these problems with “older” versions of Abinit, which I used on different CINECA machines.
Is the default selfconsistency algorithm different for simple SCF runs w.r.t. geometry optimization runs? Can this problem be related to the choice of parallelization keywords, or to the compiling options?
I am attaching the following files (adsorbed molecules on silicon slab):
* gopt28_2THYSi4x2_2oxbr.in: example geometry optimization input run
* Epot_go28_allsteps: total energies of all SCF steps of each geom opt iteration, from the .log file (i.e. I grepped ETOT)
* max_grad_go28: “max grad (force/stress)” during geom opt, from the .log file
* TEST_THYSi_U_st10go28sm.xsf.out: coordinates of the system in .xsf format, at the geom opt iteration where the problem appears (see Epot... files)
* config.log: configuration log file for the Abinit version I am using
I am not attaching the geom opt .log file itself, due to its quite large size (10.5 Mb after gzipping), but, if needed, I might extract parts of it.
Thanks a lot in advance
Best regards
Elena Molteni
Department of Physics
Universita' degli Studi di Milano
via Celoria, 16
I20133, Milano, Italy
and European Theoretical Spectroscopy Facility (ETSF)
http://www.etsf.eu
convergence problems in structure optimization
Moderator: amadon
convergence problems in structure optimization
 Attachments

 gopt28_2THYSi4x2_2oxbr.in
 geom opt input file
 (7.07 KiB) Downloaded 253 times

 Epot_go28_allsteps.out
 total energies of all SCF steps of each geom opt iteration
 (69.03 KiB) Downloaded 192 times

 max_grad_go28.out
 “max grad (force/stress)” during geom opt
 (891 Bytes) Downloaded 193 times

 TEST_THYSi_U_st10go28sm.xsf.out
 coordinates at geom opt iteration 10
 (15.26 KiB) Downloaded 198 times

 config.log
 Abinit configuration log file
 (153.57 KiB) Downloaded 156 times