Ce2O3 problem

Message

christine1201 · #1 Post by **christine1201** » Thu Aug 31, 2006 9:19 am

HI everyone.
I do some calculations about Ce2O3. I tried to calculate the lattice constant for this bulk for many times. but every time i receive a error massage : LAPACK: Routine ZPOTRF failed! 1

here is my input file
general:
System = CeO2
ISTART=0
ISPIN=2
GGA=91
EDIFF=1E-4
ENCUT = 500 eV
PREC=high
ISIF=2
IBRION=1
NFREE=10
POTIM=0.01
ALGO=Fast
ISMEAR =-5; SIGMA = 0.20 #-5 for accurate total energy and DOS 0 for large cell 1 for metal
NSW = 100
LREAL=A
MAXMIX =300
VOSKOWN =1 # 0 for PBE 1 for PW91
NSIM=4
NELM=500

LDAU=.TRUE.
LDAUTYPE=2
LDAUL= 3 -1
LDAUU= 5 0
LDAUJ=0.5 0

and my POSCAR
Ce2O3 test
1.0
3.3688388207 -1.9450000000 0.0000000000
0.0000000000 3.8900000000 0.0000000000
0.0000000000 0.0000000000 6.0295000000
2 3
Direct
0.0000000000 0.0000000000 0.0000000000
0.3333333333 0.6666666667 0.6470000000
0.6666666667 0.3333333333 -0.6470000000
0.3333333333 0.6666666667 0.2467000000
0.6666666667 0.3333333333 -0.2467000000

K-Points
0
G
14 14 8
0. 0. 0.

I used GGA-PW91 pp.
could anyone tell me how to calculate the ce2o3,please?

#2 Post by **admin** » Wed Sep 06, 2006 10:31 am

try if it helps to localize the f-electon in the core (Ce_3 PP)

elelel · #3 Post by **elelel** » Wed Sep 13, 2006 5:38 am

Hi,

You have a very valid question here! I have battled to death with this problem trying all sorts of things eg LDAUTYPE=2 or 3 and various settings therein. I always get a metallic groundstate! Can someone with a good understanding of the VASP settings (LDAU - type) for this system help us out there. Although the frozen f-states (Ce_3 PP) calculation is generally straight forward, it doesnt give a good description of the band structure for this system eg you dont get the occupied Ce-f gap state which is an experimentally observed feature for the system. However, other VASP users have obtained the observed gap state in an LDAU-type calculation eg PRB 27, 237101(2005). What settings were used for the calculation? Pliz let us in on the secret (if it should be one!). I could also add my INCAR here but I dont think its necessary. What we need is a good clarification of the settings in the LDAU section of this input file.

christine1201 · #4 Post by **christine1201** » Fri Sep 15, 2006 4:37 pm

hi, I just added AMIX = 0.2
BMIX = 0.0001
LMAXMIX = 6 in the incar. it can help to converge ce2o3.

alex · #5 Post by **alex** » Tue Sep 26, 2006 2:39 pm

Hi there,

I suggest some reading:

Phys. Rev. B 72, 237101 (2005)

Georg Kresse
Peter Blaha
Juarez L. F. Da Silva and M. Veronica Ganduglia-Pirovano
Abstract:
We show that two all-electron methods, the full-potential linearized augmented wave method and the projector augmented wave method, yield a metallic groundstate for Ce2O3, as opposed to the experimentally observed insulating groundstate. This is in contrast to previous pseudopotential calculations [Phys. Rev. B 71, 041102(R) (2005)], which suffered from an erroneous overestimation of the spin-enhancement factor and a resulting overestimation of the exchange splitting.

This does not help on your convergence problems, but it makes you feel not alone.

)

Alex

christine1201 · #6 Post by **christine1201** » Mon Oct 09, 2006 9:39 am

thanks,I have read them already. but I dont like vasp. it is to slow for me.

alex · #7 Post by **alex** » Mon Oct 16, 2006 1:55 pm

Well, looks like you are somehow wrong here.
What else program do you suggest?

alex