My Community

Hi, I am having trouble about spin-polarized structure relaxation calculation under electric field. I would like to get your suggestions.

I have tried relaxation with both nonspin polarized and spin-polarized without electric field for the same POSCAR POTCAR and KPOINT. The calculation converged. When I did calculations with electric field in Z-direction(vertical to the layer structure) I encountered problem.

The Energy minimization process :

free energy TOTEN = 2830.76856080 eV
free energy TOTEN = 1004.07686821 eV
free energy TOTEN = 297.15551832 eV
free energy TOTEN = -145.73663448 eV
free energy TOTEN = -283.11623132 eV
free energy TOTEN = -320.26891687 eV
free energy TOTEN = -330.25236451 eV
free energy TOTEN = -333.80400947 eV
free energy TOTEN = -335.09542316 eV
free energy TOTEN = -335.62929587 eV
free energy TOTEN = -335.84226343 eV
free energy TOTEN = -335.93787390 eV
free energy TOTEN = -335.97717950 eV
free energy TOTEN = -335.99531727 eV
free energy TOTEN = -336.00320627 eV
free energy TOTEN = -336.00695270 eV
free energy TOTEN = -336.00865596 eV
free energy TOTEN = -336.01002409 eV
free energy TOTEN = -336.01024008 eV
free energy TOTEN = -336.01024816 eV
free energy TOTEN = -336.01025109 eV
free energy TOTEN = -336.01025122 eV
free energy TOTEN = -336.01025127 eV
free energy TOTEN = -336.01025128 eV
free energy TOTEN = -335.95522720 eV
free energy TOTEN = -48525.95739530 eV
free energy TOTEN = 869.72763602 eV
free energy TOTEN = 318.53239816 eV
free energy TOTEN = -20849.43167751 eV
free energy TOTEN = 93.00061315 eV
free energy TOTEN = -821.90714804 eV
free energy TOTEN = -1125.22704496 eV
free energy TOTEN = -4955.62086706 eV
....
free energy TOTEN = -318.23720480 eV
free energy TOTEN = -318.20637228 eV
free energy TOTEN = -318.44216897 eV
free energy TOTEN = -317.97502871 eV
free energy TOTEN = -318.59299220 eV
free energy TOTEN = -319.28038772 eV
free energy TOTEN = -318.36778190 eV
free energy TOTEN = -50522.04076262 eV
free energy TOTEN = 881.81946244 eV
free energy TOTEN = 374.04686111 eV
free energy TOTEN = -22147.44312021 eV
free energy TOTEN = 100.52170973 eV
free energy TOTEN = 100.521710 eV

My INCAR is following :

1 NELMIN=5
2 EDIFF=1E-5 # default is 0.0001, default EDIFFG is 10*EDIFF
3 NSW=1000
4 IBRION=2
5 POTIM = 0.02
6 ISIF=1 #no cell shape and no cell volumn, no tensor calculation, just force
7 PREC=ACU
8 ISMEAR=0
9 SIGMA=0.002
10 ISPIN=2
11 ICHARG=1
12 EFIELD = 0.05
13 LDIPOL =.TRUE.
14 IDIPOL = 3
15 IALGO = 48
16 NELMDL = -24

I have tried the follwoing things in order to succeed the relaxation:

1. Line 11 . I have tried to start the calcuation from scratch or use the CHGCAR from the spin-polarized relaxation without electric field as the initial charge density.

2. Line 15, when it is commeted out, I got the error message :

WARNING: Sub-Space-Matrix is not hermitian in DAV 76

By consulting the forum, I changed the minimization from conjugate-gradient to RMM-DIIS, which get rid of the warning .

3. I also played witht eh NELMDL and POTIM , try to reduce the initial step and non-self consistent steps in the beginning.

By looking at results, I found following suspicious places ,

----------------------------------------- Iteration 1( 25) ---------------------------------------
--
---------------------------------------------------
alpha Z PSCENC = 191.85225375
Ewald energy TEWEN = 36203.81248131
-1/2 Hartree DENC = -47584.16254185
-V(xc)+E(xc) XCENC = 912.43890693
PAW double counting = 7906.85782234 -8008.57277428
entropy T*S EENTRO = 0.00000000
eigenvalues EBANDS = -2577.80737964
atomic energy EATOM = 12619.62600424
---------------------------------------------------
free energy TOTEN = -335.95522720 eV

energy without entropy = -335.95522720 energy(sigma->0) = -335.95522720
--------------------------------------------------------------------------------------------------------
----------------------------------------- Iteration 1( 26) ---------------------------------------
--
---------------------------------------------------
alpha Z PSCENC = 14363.76442025
Ewald energy TEWEN = 36203.81248131
-1/2 Hartree DENC = -47584.98661742
-V(xc)+E(xc) XCENC = 912.44411683
PAW double counting = 7906.77602572 -8008.48985413
entropy T*S EENTRO = 0.00000000
eigenvalues EBANDS = -64938.90397210
atomic energy EATOM = 12619.62600424
---------------------------------------------------
free energy TOTEN = -48525.95739530 eV

energy without entropy = -48525.95739530 energy(sigma->0) = -48525.95739530

I found the PSCENC energy and EBANDS went wrong, seriously. I would like to know the physical meaning for each of the components of the energy adding up to TOTEN?

I check the XDATCAR and found some atoms's postion goes to negative.

0.00000397 0.09037243 0.61992802
0.50000549 0.02457518 0.63189238
0.00000384 0.04049369 0.35751053
0.50000557 0.10513055 0.34465243
0.50000533 0.15737156 0.60270259
0.00000438 0.17112574 0.32587518
0.00000430 0.82890677 0.67418886
0.50000524 0.84262894 0.39729413
0.00000383 0.95955603 0.64247671
0.50000554 0.89488710 0.65530222
0.00000395 0.90962960 0.38008899
0.50000550 0.97547455 0.36811477
0.00000442 0.04299335 0.47255705
0.50000547 0.10799842 0.45988987
....
0.50000475 0.76573680 0.52211910
0.00000417 0.91275476 0.49512967
0.50000530 0.97787709 0.48314655
0.00000440 0.95697044 0.52745494
0.50000540 0.89204746 0.54010029

-0.00001221 0.09037763 0.61992257
0.49999987 0.02457832 0.63187268
-0.00000562 0.04049258 0.35750323
0.50000772 0.10513430 0.34462632
0.49999508 0.15737939 0.60270271
0.00000343 0.17111987 0.32591663
0.00000903 0.82889342 0.67423474
0.49999040 0.84261785 0.39730142
-0.00000483 0.95956663 0.64249619
0.50002752 0.89491005 0.65526224
0.00000537 0.90962891 0.38002911
0.50001530 0.97547851 0.36807304
0.00002392 0.04299607 0.47259609
0.49998814 0.10798188 0.45988687
...

Thanks for your help

Hi,

We're sorry that we didn’t answer your question. This does not live up to the quality of support that we aim to provide. The team has since expanded. If we can still help with your problem, please ask again in a new post, linking to this one, and we will answer as quickly as possible.

Best wishes,

VASP