Error in relaxation

[Samin.2]

Dear VASP users,

I am having trouble running a relaxation calculation for a 3x3x3 supercell of Cesium with one Cs atom replaced by Ho.
The calculation runs fine for a 2x2x2 supercell (a total of 16 atoms) but when I try a 3x3x3 supercell (a total of 54 atoms), VASP crashes before entering the first electronic self consistent calculation and I obtain the following error:

"Error EDDAV: Call to ZHEGV failed. Retutncode=97 2 192"

I think this may be due to my initial geometry but I think my initial settings are good. I have included both my INCAR and POSCAR files below. Any help or feedback would be greatly appreciated.

Thanks,
Adib Samin
Postdoctoral Researcher
The Ohio State University

++++++++++++++++++++++++++++++++++++++++++++++++++++
INCAR File:
++++++++++++++++++++++++++++++++++++++++++++++++++++
PREC = Accurate
ALGO = Normal
ENCUT = 300
ISTART= 0
ISPIN = 2
ISIF = 2
IBRION = 8
NSW =10
LREAL = .FALSE.
ISMEAR = 1
SIGMA = 0.2
AMIX = 0.2
BMIX = 0.0001
AMIX_MAG = 0.8
BMIX_MAG = 0.0001
NELM = 100
NELMIN= 4
EDIFF = 1.0e-06
EDIFFG = -1.0e-5

++++++++++++++++++++++++++++++++++++++++++++++++++++
POSCAR File
++++++++++++++++++++++++++++++++++++++++++++++++++++
Cubic HoCs53
18.423
1.00 0.00 0.00
0.00 1.00 0.00
0.00 0.00 1.00
1 53
Direct
0.50 0.50 0.50
0.00 0.00 0.00
0.00 0.00 0.33
0.00 0.00 0.67
0.00 0.33 0.00
0.00 0.33 0.33
0.00 0.33 0.67
0.00 0.67 0.00
0.00 0.67 0.33
0.00 0.67 0.67
0.17 0.17 0.17
0.17 0.17 0.50
0.17 0.17 0.83
0.17 0.50 0.17
0.17 0.50 0.50
0.17 0.50 0.83
0.17 0.83 0.17
0.17 0.83 0.50
0.17 0.83 0.83
0.33 0.00 0.00
0.33 0.00 0.33
0.33 0.00 0.67
0.33 0.33 0.00
0.33 0.33 0.33
0.33 0.33 0.67
0.33 0.67 0.00
0.33 0.67 0.33
0.33 0.67 0.67
0.50 0.17 0.17
0.50 0.17 0.50
0.50 0.17 0.83
0.50 0.50 0.17
0.50 0.50 0.83
0.50 0.83 0.17
0.50 0.83 0.50
0.50 0.83 0.83
0.67 0.00 0.00
0.67 0.00 0.33
0.67 0.00 0.67
0.67 0.33 0.00
0.67 0.33 0.33
0.67 0.33 0.67
0.67 0.67 0.00
0.67 0.67 0.33
0.67 0.67 0.67
0.83 0.17 0.17
0.83 0.17 0.50
0.83 0.17 0.83
0.83 0.50 0.17
0.83 0.50 0.50
0.83 0.50 0.83
0.83 0.83 0.17
0.83 0.83 0.50
0.83 0.83 0.83

[admin]

This error means that Hamilton matrix cannot be diagonalized.
It is difficult to specify what should be changed in order to resolve
this numerical problem (cell size, pseudopotential,...). The POSCAR you
attached can be run with PBE Ho_3 potential, which provides
good structures and mechanical properties.