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hi all...
i am trying to optimise a bilayer of fe/co in the bcc(111) direction with interface mixing of atoms... the program stops after 3 ionic iterations with the following error
internal error in RAD_INT: RHOPS /= RHOAE
can anybody pls tell me wat is wrong
this is my INCAR file

System = Fe/Co
ALGO = FAST
IALGO = 8 ! 8: CG, 48: DIIS algorithm for electrons
ISMEAR = 1 ! 1: Fermi
SIGMA = 0.20 ! Smearing factor
PREC = High ! sets cutoff and FFT grid
ENCUT = 300 ! planewave energy cutoff
EDIFF = 1E-07 ! energy stoping criterion for electronic iteration
#EDIFFG = -0.000001
ICHARG = 2 ! start from scratch
ISTART = 0 ! start from scratch
NPAR = 1
NBANDS = 300
ISPIN = 2
MAGMOM = 8*2.2 8*1.72
RWIGS = 1.302 1.302
!LORBIT = 11
LPLANE = .TRUE.! distribute each wave over processors
MAXMIX = 40 ! mixing tag

LREAL = .TRUE. ! use real space projection of PPs
LWAVE = .FALSE.! do write WAVECAR file
LCHARG = .FALSE. ! do write CHGCAR file
LVTOT = .FALSE. !do not write LOCPOT file

Ionic relaxation
NSW = 50 ! # of steps in optimization (default 0!)
ISIF = 3 ! 0: relax ions, 1,2:relax ions,calc stresses, 3:relax ion+cell
IBRION = 2 ! 1: quasi-NR, 2:CG algorithm for ions
NFREE = 10 ! number of DIIS vectors to save
POTIM = 0.5 ! reduce trial step in optimization
LSCALCU = .FALSE.
NSIM = 4
-------------------------------------------------------------
and this is the POSCAR
bcc iron cobalt
8.10768635308
1.00000000000 0.00000000000 0.000000000000000
-0.50000000000 0.86602540378 0.000000000000000
0.00000000000 0.000000000 1.4287
8 8
Direct
0 0 0
0.5 0 0
0 0.5 0
0.5 0.5 0
0.1666667 0.3333333 0.07142857
0.1666667 0.8333333 0.07142857
0.6666667 0.8333333 0.07142857
0.8333333 0.1666667 0.14285714
0.6666667 0.3333333 0.07142857
0.3333333 0.1666667 0.14285714
0.3333333 0.6666667 0.14285714
0.8333333 0.6666667 0.14285714
0.0000 0.000 0.21428571
0.5 0.0000 0.21428571
0.0 0.5000 0.21428571
0.5 0.5000 0.21428571
------------------------------------------------------------------------------
Kpoint file
----------------------------------------------------------------------------
Automatic
0
Monkhorst
8 8 1
0 0 0
~
.............................................
regards
asa

it makes no sense to set ISIF=3 for a system like yours (with a large vacuum region and a bilayer slab). Therefore most probably the error is a follow-up of unreasonable lattice optimization (please check the data of your geometry changes in OUTCAR to verify whether this is true). You might try to use ISIF=4 to optimize the in-plane lattice constants automatically, but I suppose that you will have to do this optimization by hand