During ionic relaxation, energy jumps dramatically

[sjtuzhanglei]

Dear gurus,

I am calculating a perovskite surface slab with adsorbed *OOH and *OO radicals. I tried to reduce POTIM to 0.05, but the energies during relaxation still sometime jump dramatically, making it difficult to converge to reliable ground state.

I also checked XDATCAR, the structure relaxations during the whole ionic steps does not vary too much or "go crazy". Thus, I am thinking there may be other factors .

Here is my INCAR:
ISTART = 0
ICHARG = 2
ISIF = 2
IDIPOL = 3
#keep these the same
ENCUT = 520.00
ISYM = 0
EDIFF = 1.E-5
GGA = PE
IBRION = 1
NSW = 200
ISMEAR = 0
SIGMA = 0.05
NELM = 500
NELMIN = 8
NELMDL = -8
ALGO = NORMAL
LDIAG = .T.

LASPH = .TRUE.
VOSKOWN = 1
LORBIT = 11
LWAVE = .FALSE.
LCHARG = .TRUE.
LREAL = AUTO

KPAR = 4
NCORE = 4

#LDA+U
LDAU=.TRUE.
LDAUTYPE=2
LDAUL=-1 -1 2 -1 -1
LDAUJ=0.0 0.0 0.0 0.0 0.0
LDAUPRINT=1
LMAXMIX=4
LDAUU= 0.0 0.0 4.0 0.0 0.0

#Magnetic Flags
ISPIN = 2
MAGMOM = 2*0.0 4*0.0 8*4.0 25*0.0
EDIFFG = -1E-3
POTIM = 0.05

Here is my POSCAR:
Ba1 La1 Co2 O6
1.00000000000000
5.4972262382999997 0.0000000000000000 0.0000000000000000
-0.0276054081000000 5.4654854758999996 0.0000000000000000
0.0109049485000000 0.0904126544000000 30.6688349671000005
Ba Pr Co O H
2 4 8 24 1
Selective dynamics
Direct
0.5002047570371886 0.0016792233053167 0.3860412617093942 F F F
0.9999159082412632 0.5014287820900165 0.3861844355107849 F F F
0.5000468442640340 0.0012405777053175 0.2551109851635260 F F F
0.5006350908432040 0.0028167276024007 0.5178066433853417 F F F
0.0000425512044160 0.5013668302642813 0.2551292132269296 F F F
0.0003935398498740 0.5024738001253084 0.5178534476942858 F F F
0.9999963680928161 0.0024343282120824 0.1951415310240847 F F F
0.0018095195494183 0.0056185273435077 0.4506558158889931 F F F
0.5001154570587900 0.5021670305706394 0.1945551499920128 F F F
0.5030254650327208 0.5054186938864191 0.4506993637969288 F F F
0.0002331871464634 0.0010894121029636 0.3205774190326380 F F F
0.9998574322427345 0.0017922837872035 0.5787686670444216 F F F
0.4999561599569162 0.5011396071123286 0.3209479615824904 F F F
0.4999391569328395 0.5019117234332384 0.5782719360635156 F F F
0.0001820407962327 0.0009336924935894 0.3889183956778837 F F F
0.4991159202658650 0.5009747736566155 0.3870565535644417 F F F
0.7499688730477274 0.7519152281892261 0.1982215544135926 F F F
0.7460070735917768 0.7475353740413766 0.4556067744369372 F F F
0.2509779912048131 0.2506568951655126 0.1981998053611704 F F F
0.2550144334364930 0.2558423157767677 0.4554285661347066 F F F
0.7476475373709164 0.2528504034200054 0.1977644148674784 F F F
0.7484097268604941 0.2502604601816998 0.4562378099525048 F F F
0.2526203320673659 0.7499171610678559 0.1977611381623419 F F F
0.2489703541686410 0.7511468336450235 0.4558636197328667 F F F
0.7555015661358766 0.7563256609343014 0.3163069158977194 F F F
0.7497381342247991 0.7518038813278523 0.5722457821879203 F F F
0.2444709851093023 0.2460869823674230 0.3162678179553140 F F F
0.2509680241996932 0.2530813513955223 0.5721353555951225 F F F
0.0002290044350559 0.0009467487247790 0.2571840966499153 F F F
0.0002186716498258 0.0029698445031414 0.5112394468243124 F F F
0.5001349637049941 0.5011601715116711 0.2587145229426611 F F F
0.5005009949774717 0.5027696160829507 0.5125209546261758 F F F
0.7457758372205134 0.2559114348197014 0.3154574889945181 F F F
0.7502376990876485 0.2530985454935148 0.5719458598620193 F F F
0.2547835265212584 0.7468172516873040 0.3153921919028804 F F F
0.2509301645268991 0.7523111318219549 0.5719360132323956 F F F
0.4591204212072982 0.4162235735161644 0.6469550460535223 T T T
0.5638656322600041 0.5143752587967642 0.6836155965612822 T T T
0.4827144451977522 0.6733907842990134 0.6879369680067875 T T T

I use 3*3*1 MP KPOINTS and POTCAR:
TITEL = PAW_PBE Ba_sv 06Sep2000
TITEL = PAW_PBE Pr_3 07Sep2000
TITEL = PAW_PBE Co 02Aug2007
TITEL = PAW_PBE O 08Apr2002
TITEL = PAW_PBE H 15Jun2001

The OSZICAR oscillates like this:
1 F= -.24221658E+03 E0= -.24220395E+03 d E =-.242217E+03 mag= 25.9292
2 F= -.24228594E+03 E0= -.24227510E+03 d E =-.693613E-01 mag= 25.8782
3 F= -.24228628E+03 E0= -.24227570E+03 d E =-.332607E-03 mag= 25.8858
4 F= -.24229100E+03 E0= -.24228024E+03 d E =-.472339E-02 mag= 25.8893
5 F= 0.16257889E+05 E0= 0.16257899E+05 d E =0.165002E+05 mag= 25.8921
6 F= 0.16562897E+05 E0= 0.16562907E+05 d E =0.305008E+03 mag= 25.8930
7 F= -.24229661E+03 E0= -.24228587E+03 d E =-.168052E+05 mag= 25.8939
8 F= 0.13430082E+04 E0= 0.13430191E+04 d E =0.158530E+04 mag= 25.8937
9 F= 0.82089158E+03 E0= 0.82090224E+03 d E =-.522117E+03 mag= 25.8929
10 F= 0.74272031E+04 E0= 0.74272138E+04 d E =0.660631E+04 mag= 25.8957
11 F= -.24230018E+03 E0= -.24228947E+03 d E =-.766950E+04 mag= 25.8960
12 F= -.24230082E+03 E0= -.24229007E+03 d E =-.640656E-03 mag= 25.8961
13 F= 0.32872674E+04 E0= 0.32872780E+04 d E =0.352957E+04 mag= 25.8972
14 F= 0.13031296E+04 E0= 0.13031403E+04 d E =-.198414E+04 mag= 25.8952
15 F= -.24230161E+03 E0= -.24229091E+03 d E =-.154543E+04 mag= 25.8953
16 F= 0.36658762E+04 E0= 0.36658864E+04 d E =0.390818E+04 mag= 25.8946
17 F= -.19138026E+03 E0= -.19136998E+03 d E =-.385726E+04 mag= 25.8895
18 F= -.24226896E+03 E0= -.24225874E+03 d E =-.508887E+02 mag= 25.8885
19 F= -.24227058E+03 E0= -.24226063E+03 d E =-.162015E-02 mag= 25.8918
20 F= -.24227456E+03 E0= -.24226434E+03 d E =-.397953E-02 mag= 25.8881
21 F= -.24228784E+03 E0= -.24227770E+03 d E =-.132768E-01 mag= 25.8882
22 F= -.24224118E+03 E0= -.24223130E+03 d E =0.466599E-01 mag= 25.8831
23 F= -.24223336E+03 E0= -.24222356E+03 d E =0.781753E-02 mag= 25.8817
24 F= -.24222502E+03 E0= -.24221529E+03 d E =0.834143E-02 mag= 25.8813
25 F= -.24218383E+03 E0= -.24217443E+03 d E =0.411943E-01 mag= 25.8812
26 F= -.24214702E+03 E0= -.24213791E+03 d E =0.368031E-01 mag= 25.8979
27 F= -.24218085E+03 E0= -.24217349E+03 d E =-.338230E-01 mag= 26.0447
28 F= -.24217782E+03 E0= -.24217053E+03 d E =0.302366E-02 mag= 26.0427
29 F= 0.24889296E+05 E0= 0.24889303E+05 d E =0.251315E+05 mag= 26.0321
30 F= 0.40347135E+03 E0= 0.40347864E+03 d E =-.244858E+05 mag= 26.0338
31 F= -.24214854E+03 E0= -.24214121E+03 d E =-.645620E+03 mag= 26.0327
32 F= -.24214760E+03 E0= -.24214027E+03 d E =0.944322E-03 mag= 26.0323
33 F= -.24213997E+03 E0= -.24213270E+03 d E =0.762709E-02 mag= 26.0317
34 F= -.24213936E+03 E0= -.24213205E+03 d E =0.612125E-03 mag= 26.0311
35 F= 0.98055656E+02 E0= 0.98063034E+02 d E =0.340195E+03 mag= 26.0305
36 F= 0.11614409E+04 E0= 0.11614483E+04 d E =0.106339E+04 mag= 26.0310
37 F= -.24214692E+03 E0= -.24213954E+03 d E =-.140359E+04 mag= 26.0323
38 F= 0.36708473E+04 E0= 0.36708547E+04 d E =0.391299E+04 mag= 26.0327
39 F= -.21624626E+03 E0= -.21623893E+03 d E =-.388709E+04 mag= 26.0329
40 F= -.24214158E+03 E0= -.24213420E+03 d E =-.258953E+02 mag= 26.0327
41 F= 0.12499562E+05 E0= 0.12499570E+05 d E =0.127417E+05 mag= 26.0357
42 F= 0.41190189E+03 E0= 0.41190910E+03 d E =-.120877E+05 mag= 26.0419
43 F= 0.52188807E+04 E0= 0.52188880E+04 d E =0.480698E+04 mag= 26.0326
44 F= -.24201875E+03 E0= -.24201139E+03 d E =-.546090E+04 mag= 26.0316
45 F= -.24215045E+03 E0= -.24214284E+03 d E =-.131700E+00 mag= 26.0295
46 F= -.96323793E+02 E0= -.96316373E+02 d E =0.145827E+03 mag= 26.0321

Thank you!

[admin]

Your calculated dipole moment is apparently unstable,
fluctuating in the cell. Better convergence can be achieved
using e.g. smaller mixing parameters.
Another point is that atomic positions, which are kept
frozen, are not very well converged. When the structure is better
relaxed the danger of the fluctuation of the magnetic moment becomes
smaller.

[sjtuzhanglei]

Thank you, admin,

I will try smaller mixing parameters.

I first converged the slab, and then freeze them when calculating molecule adsorption, so I believe the slab is good to be frozen for now?

Sincerely,