[Pw_forum] Question about volume relaxation - reg

[Muthu V]

Dear Users
In every volume relaxation run ,
     ........
     A final scf calculation at the relaxed structure.
     The G-vectors are recalculated for the final unit cell
     Results may differ from those at the preceding step.
     ........
is being printed. what i have notice is that after this a final scf is
being done with input celldm(i) and optimized atomic coordinate.but the
message leading the view that we are doing scf for optimized structure (
cell parameter + atomic coordinates ).
for example i did volume relax for 2H-MoS2. the  input celldm(i) are
celldm(1)=   5.973424 and celldm(3)=   3.889592.
the relaxed cell parameter values are
      Begin final coordinates
     CELL_PARAMETERS (alat=  5.97342433)
        1.010051108   0.000000000   0.000000000
       -0.505025554   0.874729919   0.000000000
       -0.000000000  -0.000000000   4.288136193
but for final scf calculation QE taking celldim(i) as ( though the relaxed
celldm are different) celldm(1)=   5.973424, celldm(3)=   3.889592
Why this scf is done with optimized atomic coordinate and old celldm(i)s ?
what is the physics behind such a run?
Thank you
---------------------------------
Muthu V
Sri Paramakalyani College
Alwarkurichi,India
----------------------------------
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20160624/8271e7c0/attachment.html>