[Pw_forum] Relaxation of Na(100)

[naser zare]

Dear all
  Hello
        I am studying about relaxation of  Na(100) .I use "GGA(PBE)"  for XC .I have worked on that issue(relaxation)  with k-point mesh equal 32×32×1 ,and  Ecut range of 25 to 35Ry  for wavefunction and Ecut=140Ry up to 350 Ry  for charge density .I run program based on presented ranges ,and also used two smearing model(gauss and methfessel-paxton). However,forces had not been reach below 0.0001 Ry/a.u  ,but approximately 0.0005 Ry/a.u . It should be stated that I reduced dt from 20.DO to 2.D0 step by step in relaxation ,but I have not reached forces below 0.0001 Ry/a.u yet.
  I should state that I have this difficult for slab with 7 layers and more, that number of atoms in supercell is more than 7 atoms.
  I should state that my main question is about reaching 0.0001 Ry/a.u and what can I do for that?, and I was wondering if you could help me. Thank you for your attention.
  Best regards,
  Nasser Zare Dehnavi 

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