[Wien] Confusion regarding the convergence of a supercell and the parallel calculation

[Anupriya Nyayban]

Dear experts and users,

I am trying to find the convergence for a 2*2*1 supercell of a doped
orthorhombic ABX3 type structure (the system specification is provided
below). The space group is Pnma for the pure structure and it changes to
P-1 for the doped supercell. The supercell also consists of 80 atoms among
which 40 are inhomogenes. The scf is calculated with "run_lapw -p -ec
0.0001 -cc 0.001 -fc 1". Forces on some atoms are more than 5 mRy/a.u.
(maximum 6.629 mRy/a.u.). Should we go for geometry minimization ? Whether
the changed space group is correct or not.
The scf is working fine for the RKmax=7 whereas lapw2 crashes (stating
forrtl: severe (67): input statement requires too much data, unit 10) for
Rkmax=8 and kmesh 4*9*5. Is it fine to proceed with RKmax=7?



And also, the parallel calculation is running in a HPC (Processor: dual
socket 18 core per socket intel skylake processor, RAM: 96 GB ECC DDR4 2133
MHz RAM in balanced configuration, Operating system: CentOS-7.3, using
compiler/intel 2018.5.274). OMP_NUM_THREADS=40 is set in the bashrc file.
The last few lines of .machine reads as
"1: localhost
 1:localhost
granularity:1
extrafine:1
#uncomment for specific OMP_parallelization (overwriting a global
OMP_NUM_THREAD)
#omp_global:4
#or use program-specific parallelization:
#omp_lapw0:4
#omp_lapw1:4
#omp_lapw2:4
#omp_lapwso:4
#omp_dstart:4
#omp_sumpara:4
#omp_nlvdw:4"
I am a little bit confused about how the parallel distribution is made and
whether we are using the system maximally for the calculation or not. I am
using parallel calculation for the first time.

Looking forward to your valuable opinion.


Thank you in advance.



-- 
With regards
Anupriya Nyayban
Ph.D. Scholar
Department of Physics
NIT Silchar
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