how to keep the spin states during the relaxation

[zongtan_fang1]

Hi,

I am having an issue of spin state change on a specific Ni atom in my NMC (Ni, Mn, Co) system during relaxation in my GGA+U calculations.

The initial ionic step gives Ni3+, then gradually lost spin to Ni4+ during the relax.

Also my GGA PBE calculation without U is able to keep Ni3+ unchanged.

I am wondering if there is a way to keep the spin state for GGA+U?

I also tried reading WAVECAR from PBE to do PBE+U, still converged to a different state.
NUPDOWN also didn't help.

I am using the following INCAR for GGA+U; any comment or suggestion is welcomed.

Thanks.


=========================================
Electronic relaxation:
ENCUT = 480.0 ! Cutoff energy for plane waves basis set in eV
ALGO = Fast ! A Davidson blocked iteration scheme
NELMIN = 4 ! Minimum number of eletronic selfconsistency (SC) steps
NELM = 500 ! Maximum number of electronic SC steps
NELMDL = -8 ! Number of NON-selfconsistency steps
EDIFF = 1.0E-6 ! Global-break condition for the electronic SC-loop (ELM)
AMIX = 0.4
BMIX = 1.000

Calculation mode:
PREC = Accurate ! Calculation level (Changes FFT-grids)
ISPIN = 2 ! spin-polarized calculations
ADDGRID = .TRUE. ! PAW flag

LREAL=.FALSE. ! Should not be used for final total energy calculations
LWAVE=.FALSE.
LCHARG=.FALSE.

Ionic relaxation:
NSW = 500 ! Number of ionic steps
EDIFFG = -0.03 ! stop if all forces are smaller than |EDIFFG|
IBRION = 2 !
ISIF = 3 ! Force, stress, relax ions, keep cell shape, keep cell volume
POTIM = 0.02

Integration over the Brillouin zone (BZ):
ISMEAR = 0 !
SIGMA = 0.05

DOS calculation:
LORBIT = 11 ! Calculate the DOS without providing the Wigner Seitz radius
NEDOS = 1001 ! Number of points to calculate the DOS

MAGMOM=120*0 60*0 36*2 12*4 12*0

GGA+U Calculations:
LDAU = .TRUE.
LDAUTYPE = 2
LDAUL = -1 -1 2 2 2
LDAUU = 0 0 5.96 5.1 5.0
LDAUJ = 0 0 0 0 0
LMAXMIX = 4

INIWAV = 1 ! initial guess
ISTART = 0 ! from scratch
ICHARG = 2 ! Take superposition of atomic charge densities

VOSKOWN = 1 ! Vosko-Wilk-Nusair interpolation is used
NBLOCK = 1
NWRITE = 1

NPAR=8
=======================

[support_vasp]

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