[Wien] Force Convergence Criteria/It-number

[Judy Cherian]

Hello all,

I am doing SCF calculation on displacement files created by phonopy.(
Displacements files were made using a p-type supercell created from struct
file after performing Force convergence and Volume optimization with
minimization of internal parameters). There are 44 atoms in the unit cell.
When doing the SCF calculation using w2web interface, I chose the 0.01
mRy/a.u as the force convergence requirement. The calculation ends with the
day file telling that force convergence was met. However, when I look at the
total force at the end of .scf file, the force on each atom is much higher
that 0.01 mRy/a.u. I was wondering how SCF determines when the force
convergence is met. Is it by the Total Forces on each atom , or something
else?

Also, how can I increase the number of iterations in scf cycle? Does
checking the It-number in w2web Interface ( in the Run SCF menu) and
changing the value from the default value of 40 to some other value increase
the number of iterations? Is there a limit on the iteration number?

Thank you

Judy Cherian
Graduate Student
NHMFL/FSU
Tallahassee-Florida
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