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cation (Fe) vacancy and we have generated it by deleting one Fe atom from
the supercell. Final structure, hence, contains 111 atoms and all other
occupancies at different lattice sites are well matched with Rietveld
analysis of experimental XRD. I am using 2 k points for this 111 atom
supercell. But even after 60 iterations the convergence achieved are as
follows:

   cc: 0.234...    cc was set to 0.001
   ec: 0.063...    ec was set to 0.0001

Sir, my question are:
1) As the supercell is merely an extension of the 56 atoms unit cell with
more accurate values of atomic occupancies as in the experimental structure,
why it should at all taking so much time to converge?

2) We have *created one defect by creating a Fe vacancy*...*is it that the
structures having defect take more time to converge?.*..but as far as our
analysis until now..the structure should have one Fe vacancy per 112
atoms...

3) As we have obtained converged solutions for 56 atom cell by using 14 k
points..*is it that we should use 7K points for 111 atom supercell
calculation*?..is 2 K points are actually small in order to achieve
convergence of this structure?

Any response in this regard will be very helpful for us. Thanks in advance.

with regards,

-- 
Shamik Chakrabarti
Senior Research Fellow
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA

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Dear wien2k users,<div><br></div><div>=A0=A0 =A0 =A0 =A0I have performed a =
56 atom / unit cell calculation for a ferrimagnetic material. It was well c=
onverged both in energy and charge by 60 iterations. 14 K points were used =
for this calculation. Then I have generated a 2x1x1 supercell having 112 at=
oms / supercell. This was done to achieve better experimental model as obta=
ined through Rietveld analysis. From Rietveld analysis it was also seen tha=
t for 112 atoms we can consider a cation (Fe) vacancy and we have generated=
 it by deleting one Fe atom from the supercell. Final structure, hence, con=
tains 111 atoms and all other occupancies at different lattice sites are we=
ll matched with Rietveld analysis of experimental XRD. I am using 2 k point=
s for this 111 atom supercell. But even after 60 iterations the convergence=
 achieved are as follows:</div>
<div><br></div><div>=A0=A0 cc: 0.234... =A0 =A0cc was set to 0.001</div><di=
v>=A0=A0 ec: 0.063... =A0 =A0ec was set to 0.0001</div><div><br></div><div>=
Sir, my question are:</div><div>1) As the supercell is merely an extension =
of the 56 atoms unit cell with more accurate values of atomic occupancies a=
s in the experimental structure, why it should at all taking so much time t=
o converge?</div>
<div><br></div><div>2) We have <b>created one defect by creating a Fe vacan=
cy</b>...<b>is it that the structures having defect take more time to conve=
rge?.</b>..but as far as our analysis until now..the structure should have =
one Fe vacancy per 112 atoms...</div>
<div><br></div><div>3) As we have obtained converged solutions for 56 atom =
cell by using 14 k points..<b>is it that we should use 7K points for 111 at=
om supercell calculation</b>?..is 2 K points are actually small in order to=
 achieve convergence of this structure?</div>
<div><br></div><div>Any response in this regard will be very helpful for us=
. Thanks in advance.</div><div><br></div><div>with regards, =A0<br clear=3D=
"all"><div><br></div>-- <br>Shamik Chakrabarti<br>Senior Research Fellow<br=
>
Dept. of Physics &amp; Meteorology<br>Material Processing &amp; Solid State=
 Ionics Lab<br>IIT Kharagpur<br>Kharagpur 721302<br>INDIA<br>
</div>

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