[Pw_forum] different forces between last 2 steps

[Jaret Qi]

Dear QE users,Why total forces are different in the last relaxation step and the final step that pw.x performs once the criteria satisfies, does this mean relaxation not good?take a look :
     Forces acting on atoms (Ry/au):
     atom    1 type  2   force =    -0.00000948   -0.00000948   -0.00002573     atom    2 type  1   force =     0.00000206    0.00000206   -0.00000197     atom    3 type  3   force =    -0.00001812   -0.00001812    0.00001050     atom    4 type  3   force =     0.00006085   -0.00003531    0.00000860     atom    5 type  3   force =    -0.00003531    0.00006085    0.00000860
     Total force =     0.000108     Total SCF correction =     0.000000================================================================================     bfgs converged in  49 scf cycles and  44 bfgs steps     (criteria: energy <  1.0E-05, force <  1.0E-04, cell <  5.0E-01)
     End of BFGS Geometry Optimization          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.================================================================================
     Forces acting on atoms (Ry/au):
     atom    1 type  2   force =    -0.01460576   -0.01460576   -0.01547886     atom    2 type  1   force =    -0.00396741   -0.00396741   -0.00495319     atom    3 type  3   force =    -0.02514170   -0.02514170    0.04303246     atom    4 type  3   force =     0.04519347   -0.00147860   -0.01130020     atom    5 type  3   force =    -0.00147860    0.04519347   -0.01130020
     Total force =     0.090460     Total SCF correction =     0.000000


Regards,JaretASU
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