[QE-users] query about system dependent etot_conv_thr, forc_conv_thr and conv_thr

[Dr. K. C. Bhamu]

Dear QE Users,

For simple compounds (binary or ternary), I know the said parameters may be
fixed tight  (etot_conv_thr, 1e-5,  and forc_conv_thr, 1e-5 and conv_thr.
1d-07 or 1d-08 or 1d-09). But for complex systems, if we set them high then
it would cost much wall time.

To avoid this, Is there any thumb rule to decide the above parameters to be
kept fix for complex bulk structures (having a combination of organic and
inorganic elements), i.e. as the number of atoms increases in the system
the above parameters can be lowered?
As far as I know, these parameters have much importance if we see per atom.
So, if we increase the number of atoms the parameters can be lowered (Ex.
for hybrid perovskites with 36 atoms in a unit cell, etot_conv_thr, 1e-3,
and forc_conv_thr, 1e-3 and conv_thr. 1d-06 ), is it?


Any comment will be helpful to improve my understanding or in correcting me
if I am wrong, also will save computational cost.


Thanks and regards,


Dr. K. C. Bhamu
National Postdoctoral Fellow,
Physical and Materials Chemistry Division
CSIR-NCL, Pune
Mob. No.  +91-9975238952
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