[Wien] Questions about anatase TiO2
phedra phedra
phedra76 at hotmail.com
Wed Feb 16 08:29:27 CET 2005
Dear Wien users and developers,
I am calculating DOS and bandstructure of anatase TiO2 using Wien2004 with
the REDHAT LINUX 9.0 and PGI5.0 compiler. According to the literatures, the
parameters are as the follow: space group 141/amd, a=b=3.784 c=9.515
(angstrom), u=0.208. So I give the following position for Ti and O
respectively.
Ti (0,0,0) (0.5,0.5,0.5) (0.5,0,0.75) (0.5,0,0.75) (0,0.5,0.75)
O (0, 0, 0.208) (0, 0,0.792) (0.5,0.5,0.708) (0.5,0.5,0.292)
(0,0.5,0.042) (0,0.5,0.458) (0.5,0,0.458) (0.5,0,0.958)
Before the initialization of calculation, I chose the Lattice type as P.
After I clicked “x sgroup” and “view outputsgroup” from w2web, there
also occured “Warning!!! Bravais Lattice has changed. Sgroup found:
141(141/a m d)[origin choice 2]. ” I started a new session, chose the
lattice type as 141/amd and input the above atom positions. But after I
saved the structure, the position automatically changed as the follow:
Ti (0,0,0) (0.5, 0.5, 0.5) (0.5, 0, 0.75) (0, 0.5, 0.25)
O (0, 0, 0.208) (0, 0, 0.792) (0.5, 0.5, 0.708) (0.5, 0.5, 0.292)
(0, 0.5, 0.042) (0, 0.5, 0.458) (0.5, 0, 0.542) (0.5, 0, 0.958)
So I had to calculated the scf cycles using the changed position. The
bandgap for anatase TiO2 is about 3.2eV(experimental) and 2.0eV(calculated
by other author using LAPW method). But I can not find the appreciable gap
in the plots for DOS and bandstructure. Furthermore I can’t obtain the DOS
with energy high than 0eV even if I increased Emax to 2.5 in case.in1.
I have 3 questions:
1. I think the calculated result is not correct since no gap can be found.
But i do not know where the problem is. Does it come from atom position or
other aspects?
2. The calculated Fermi energy is about 1.4eV, which seems to be higher
than that of other compounds. Is the DOS with low energy related with the
higher Fermi level?
3. The last iteration of case.scf is as the follow:
ATOMIC SPHERE DEPENDENT PARAMETERS FOR ATOM Ti
OVERALL ENERGY PARAMETER IS 0.3000
OVERALL BASIS SET ON ATOM IS LAPW
E( 0)= 0.3000
LAPW
E( 0)= -4.3500
LOCAL ORBITAL
E( 1)= -2.5800
LAPW
E( 1)= 0.3000
LOCAL ORBITAL
E( 2)= 0.3000 E(BOTTOM)= 0.100 E(TOP)= -200.000
LAPW
ATOMIC SPHERE DEPENDENT PARAMETERS FOR ATOM O
OVERALL ENERGY PARAMETER IS 0.3000
OVERALL BASIS SET ON ATOM IS LAPW
E( 0)= -1.5500 E(BOTTOM)= -2.700 E(TOP)= -200.000
LAPW
E( 0)= 0.3000
LOCAL ORBITAL
E( 1)= 0.3000
LAPW
K= 0.25000 0.25000 0.25000 1
:RKM : MATRIX SIZE 990LOs: 24 RKM= 6.00 WEIGHT= 8.00
I know the correct relation should be E(bottom)<E(l)<E(top).But the
obtained E(l) is not located between E(bottom) and E(top). It seems that
E(top) are not found since -200 is the default value. Where is problem and
how can I solve it?
The case.struct, case.in1, case.in2 and case.scf files are attached.
Any comments will be greatly appreciated.
Best regards
Phedra
File TiO2.struct
TiO2
B LATTICE,NONEQUIV.ATOMS: 2141_I41/amd
MODE OF CALC=RELA unit=ang
7.150727 7.150727 17.980751 90.000000 90.000000 90.000000
ATOM -1: X=0.00000000 Y=0.00000000 Z=0.00000000
MULT= 4 ISPLIT= 8
-1: X=0.25000000 Y=0.75000000 Z=0.25000000
-1: X=0.00000000 Y=0.50000000 Z=0.00000000
-1: X=0.25000000 Y=0.25000000 Z=0.75000000
Ti NPT= 751 R0=0.00005000 RMT= 1.4000 Z: 22.0
LOCAL ROT MATRIX: 0.0000000 0.0000000 1.0000000
1.0000000 0.0000000 0.0000000
0.0000000 1.0000000 0.0000000
ATOM -2: X=0.00000000 Y=0.00000000 Z=0.20800000
MULT= 8 ISPLIT= 8
-2: X=0.00000000 Y=0.00000000 Z=0.79200000
-2: X=0.25000000 Y=0.75000000 Z=0.45800000
-2: X=0.25000000 Y=0.75000000 Z=0.04200000
-2: X=0.00000000 Y=0.50000000 Z=0.20800000
-2: X=0.00000000 Y=0.50000000 Z=0.79200000
-2: X=0.25000000 Y=0.25000000 Z=0.95800000
-2: X=0.25000000 Y=0.25000000 Z=0.54200000
O NPT= 621 R0=0.00010000 RMT= 1.2000 Z: 8.0
LOCAL ROT MATRIX: 0.0000000 0.0000000 1.0000000
1.0000000 0.0000000 0.0000000
0.0000000 1.0000000 0.0000000
16 NUMBER OF SYMMETRY OPERATIONS
1 0 0 0.0000000
0-1 0 0.0000000
0 0-1 0.0000000
1
-1 0 0 0.0000000
0-1 0 0.0000000
0 0-1 0.0000000
2
1 0 0 0.0000000
0 1 0 0.0000000
0 0 1 0.0000000
3
-1 0 0 0.0000000
0 1 0 0.0000000
0 0 1 0.0000000
4
0 1 0 0.7500000
1 0 0 0.2500000
0 0-1 0.7500000
5
0-1 0 0.2500000
-1 0 0 0.2500000
0 0-1 0.7500000
6
1 0 0 0.5000000
0 1 0 0.0000000
0 0-1 0.5000000
7
1 0 0 0.5000000
0-1 0 0.0000000
0 0 1 0.5000000
8
0-1 0 0.7500000
1 0 0 0.2500000
0 0 1 0.7500000
9
0 1 0 0.7500000
-1 0 0 0.2500000
0 0-1 0.7500000
10
-1 0 0 0.5000000
0 1 0 0.0000000
0 0-1 0.5000000
11
-1 0 0 0.5000000
0-1 0 0.0000000
0 0 1 0.5000000
12
0 1 0 0.2500000
1 0 0 0.2500000
0 0 1 0.7500000
13
0-1 0 0.7500000
-1 0 0 0.2500000
0 0 1 0.7500000
14
0-1 0 0.2500000
1 0 0 0.2500000
0 0-1 0.7500000
15
0 1 0 0.2500000
-1 0 0 0.2500000
0 0 1 0.7500000
16
File TiO2.in1
WFFIL (WFPRI, SUPWF)
6.00 10 4 (R-MT*K-MAX; MAX L IN WF, V-NMT
0.30 5 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
APW/LAPW)
0 0.30 0.000 CONT 0
0 -4.35 0.000 STOP 0
1 -2.58 0.000 CONT 0
1 0.30 0.000 CONT 0
2 0.30 0.010 CONT 0
0.30 3 0 (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global
APW/LAPW)
0 -1.55 0.010 CONT 0
0 0.30 0.000 CONT 0
1 0.30 0.000 CONT 0
K-VECTORS FROM UNIT:4 -9.0 2.5 emin/emax window
File TiO2.in2
TOT (TOT,FOR,QTL,EFG,FERMI)
-9.0 96.0 0.50 0.05 EMIN, NE, ESEPERMIN, ESEPER0
TETRA 0.000 (GAUSS,ROOT,TEMP,TETRA,ALL eval)
0 0 2 0 2 2 -2 2 4 0 4 2 -4 2 4 4 -4 4 6 0 6 2 -6 2 6 4 -6 4 6 6
-6 6
0 0 1 1 -1 1 2 0 2 2 -2 2 3 1 -3 1 3 3 -3 3 4 0 4 2 -4 2 4 4 -4 4
5 1 -5 1 5 3 -5 3 5 5 -5 5 6 0 6 2 -6 2 6 4 -6 4 6 6 -6 6
14. GMAX
FILE FILE/NOFILE write recprlist
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