Dear wien2k users,<div><br></div><div> We are running a SCF calculation for a <b>56 inequivalent atoms</b> unit cell. We have included spin polarization and self interaction correction (GGA+U) in this calculation. The calculation has been run for one week now without any errors. We are using a system having <b>Intel Xeon quad core processor and 8GB RAM</b>. We are using <b>14 K points</b> and a <b>mixing factor 0.1</b>. The energy and charge convergence were achieved up to <b>0.04</b>. Once energy convergence has also gone up to 0.008 but then again a bit diverges to come up to 0.04. Now my question is::</div>
<div><br></div><div>(1) Is it possible to achieve charge and energy convergence up to 0.0001 with this unit cell using the above mentioned system if we consider that all the interactions applied for this </div><div> material is proper? </div>
<div>(2) If it is achievable then can we estimate how much time it can take given the no. of inequivalent atoms, K points, mixing parameter and nature of the processor?</div><div> </div><div>(3) If we are not able to achieve that much of convergence (0.0001) even after a long time (say 2 weeks) then is it right to stop the calculation if we achieve a stability in convergence</div>
<div> and say it is up to 0.01? </div><div>(4) If we take the convergence up to 0.01 then how much reliable will be the further calculation of its properties (DOS) given the no. of K points is 14?</div><div><br></div><div>
(5) If we do not get the convergence say at least up to 0.01 is it right to increase the mixing parameter to say 0.15 or 0.20 given the system is a <b>localized magnetic system</b>?</div><div><br></div><div>The system is an insulator and also contain Fe. Thats why we have also consider self interaction correction (GGA+U).</div>
<div><br></div><div>Please forgive us for such a long email. We have to right it in this way as the calculation has already been taken a long time and are indicating to take longer time still.</div><div>Any reply in this regard will be very helpful for us. Thanks in advance.</div>
<div><br></div><div>with best regards, </div><div><br>-- <br>Shamik Chakrabarti<br>Research Scholar<br>Dept. of Physics & Meteorology<br>Material Processing & Solid State Ionics Lab<br>IIT Kharagpur<br>Kharagpur 721302<br>
INDIA<br>
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