structure relaxation problem

[andy]

Dear everyone:
I carried out the structure relaxation with follow parameters:
************************
SYSTEM = BiVO4_mono
ISTART = 0
ICHARG = 2
ENCUT = 550
EDIFF = 1E-4
PREC = Accurate
LREAL = .FALSE.
ISYM = 2
ISMEAR = -5
NSW = 100
ISIF = 3
IBRION = 1
POTIM = 0.2315
EDIFFG = -1E-2
*************************
And at last it reached required accuracy with 7 step. What I want to know is:
(a) what kinds of FORCE are controlled by the parameter EDIFFG? In the OUTCAR file, there are three FORCE: “FORCE on cell�, “FORCES acting on ions�, and “TOTAL-FORCE (eV/Angst)�. Which one has relation with EDIFFG?
(b) If the relaxation stopped when the “TOTAL-FORCE (eV/Angst)� acting on each atom reach EDIFFG, then I found the last 3 steps all fulfill the EDIFFG. Why does not the relaxation stop at the fifth step?
POSITION TOTAL-FORCE (eV/Angst)
-----------------------------------------------------------------------------------
-1.85198 2.59492 2.39872 0.000696 -0.003673 -0.004428
-3.87795 -0.55920 -0.55325 -0.009908 0.004660 0.009555
-3.30994 0.00582 2.39872 -0.000696 0.003673 -0.004428
-1.28397 3.15994 -0.55325 0.009908 -0.004660 0.009555
-3.31828 -2.57537 -2.39872 -0.000696 0.003673 0.004428
-1.29230 0.57874 0.55325 0.009908 -0.004660 -0.009555
-1.86031 0.01373 -2.39872 0.000696 -0.003673 0.004428
-3.88629 -3.14039 0.55325 -0.009908 0.004660 -0.009555
-2.58096 1.30037 1.47788 0.000000 0.000000 -0.001474
-2.58930 -1.28082 -1.47788 0.000000 0.000000 0.001474
-2.58096 1.30037 -4.40158 0.000000 0.000000 0.003258
-2.58930 -1.28082 4.40158 0.000000 0.000000 -0.003258
-----------------------------------------------------------------------------------
total drift: 0.000000 0.000000 0.000000

POSITION TOTAL-FORCE (eV/Angst)
-----------------------------------------------------------------------------------
-1.85188 2.59475 2.39865 -0.000713 -0.004281 -0.006871
-3.87810 -0.55929 -0.55314 -0.005172 0.001284 0.008645
-3.30995 0.00574 2.39865 0.000713 0.004281 -0.006871
-1.28373 3.15978 -0.55314 0.005172 -0.001284 0.008645
-3.31839 -2.57541 -2.39865 0.000713 0.004281 0.006871
-1.29217 0.57863 0.55314 0.005172 -0.001284 -0.008645
-1.86032 0.01360 -2.39865 -0.000713 -0.004281 0.006871
-3.88654 -3.14044 0.55314 -0.005172 0.001284 -0.008645
-2.58092 1.30024 1.47781 0.000000 0.000000 -0.004004
-2.58936 -1.28090 -1.47781 0.000000 0.000000 0.004004
-2.58092 1.30024 -4.40152 0.000000 0.000000 0.002349
-2.58936 -1.28090 4.40152 0.000000 0.000000 -0.002349
-----------------------------------------------------------------------------------
total drift: 0.000000 0.000000 0.000000

POSITION TOTAL-FORCE (eV/Angst)
-----------------------------------------------------------------------------------
-1.85184 2.59459 2.39854 -0.000480 -0.003329 -0.006077
-3.87815 -0.55936 -0.55301 -0.004597 0.001849 0.007626
-3.30989 0.00576 2.39854 0.000480 0.003329 -0.006077
-1.28357 3.15970 -0.55301 0.004597 -0.001849 0.007626
-3.31839 -2.57536 -2.39854 0.000480 0.003329 0.006077
-1.29207 0.57858 0.55301 0.004597 -0.001849 -0.007626
-1.86034 0.01347 -2.39854 -0.000480 -0.003329 0.006077
-3.88665 -3.14048 0.55301 -0.004597 0.001849 -0.007626
-2.58086 1.30017 1.47770 0.000000 0.000000 -0.004110
-2.58936 -1.28095 -1.47770 0.000000 0.000000 0.004110
-2.58086 1.30017 -4.40152 0.000000 0.000000 0.001327
-2.58936 -1.28095 4.40152 0.000000 0.000000 -0.001327
-----------------------------------------------------------------------------------
total drift: 0.000000 0.000000 0.000000

Thanks a lot.

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