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Input
Below a sample input is shown for TiO2 (rutile), one of the
test cases provided in the WIEN97 package. The input file is
written automatically by LSTART.
------------------ top of file: case.in1 --------------------
WFFIL (WFPRI,WFFIL,SUPWF ; wave fct. print,file,suppress
8.000 12 4 (R-MT*K-MAX; MAX l, max l for hns )
0.30 5 (global energy parameter E(l), with 5 other choices)
0 -3.00 0.020 CONT ENERGY PARAMETER for s
0 0.30 0.000 CONT ENERGY PARAMETER for s-local orbital
1 -1.90 0.020 CONT ENERGY PARAMETER for p
1 0.30 0.000 CONT ENERGY PARAMETER for p-local orbitals
2 0.20 0.020 CONT
0.20 1 (global energy parameter E(l), with 1 other choice)
0 -0.90 0.020 STOP
K-VECTORS FROM UNIT:5
GAMMA 0 0 0 2 1.00 -1.2 1.0
2 K-VEC 1 0 0 2 2.00
3 K-VEC 1 1 0 2 1.00
4 K-VEC 0 0 1 2 1.00
5 K-VEC 1 0 1 2 2.00
6 K-VEC 1 1 1 2 1.00
END
------------------- bottom of file ------------------------
Interpretive comments follow:
- line 1:
- format(A5)
switch
WFFIL standard option, writes wave functions to file
case.vector (needed in lapw2)
SUPWF suppresses wave function calculation (faster for testing
eigenvalues only)
WFPRI prints eigenvectors to case.output1 and writes
case.vector (produces long outputs!)
- line 2:
- free format
rkmax, lmax, lnsmax
rkmax
Rmt * Kmax determines matrix size (convergence),
where Kmax is the plane wave cut-off, Rmt is the
smallest of all atomic sphere radii. This value
should be between 6 and 10. (Kmax2 would be
the plane wave cut-off parameter in Ry used in
pseudopotential calculations.) Note that d (f) wavefunctions
converge slower than s and p. For systems including
hydrogen with short bondlength and thus a very
small Rmt (e.g. 0.7 a.u.), rkmax = 3 might already be
reasonable, but convergence must be checked for a
new type of system.
Note, that the actual matrix size is written on
case.scf1. It is determined by whatever is
smaller, the plane wave cut-off (specified with rkmax)
or the matrix dimension NMAT, (see previous section).
lmax maximum l value for partial waves used inside atomic
spheres (should be between 8 and 12)
lnsmax maximum l value for partial waves in the
computation of non-muffin-tin matrix
elements (lnsmax=4 is quite good)
- line 3:
- free format
Etrial, ndiff
Etrial default energy used for all El to obtain
ul(r,El) as
regular solution of the radial Schrödinger equation
[used in equ.2.5,2.8] (see figure
7.1).
ndiff number of exceptions (specified in the next ndiff lines)
- line 4:
- format(I2,2F10.5,A4)
l, El, de, switch
l l of partial wave
El El for L=l
de energy increment
de=0: this E(l) overwrites the default energy (from line 3)
de
0: a search for a resonance energy using this
increment is done. The radial function ul(r,E) up to
the muffin-tin radius RMT varies with the energy. A typical
case is represented in Fig. 7.1.
At the bottom of the energy bands u has a zero slope
(bonding state), but it has a zero value (antibonding state)
at the top of the bands. One can search up and down in
energy starting with El using the increment de to find
where
ul(RMT,E) changes sign in value to
determine Etop and in slope to specify
Ebottom.
If both are found El is taken as the arithmetic mean and
replaces the trial energy. Otherwise El keeps the specified
value. For Etop and
Ebottom
bounds of +1 and -10 Ry are defined respectively, and
if they are not found, they remain at the initial value set to -200.
switch used only if de.ne.0
CONT calculation continues, even if either Etop or
Ebottom are not found
STOP calculation stops if not both Etop and
Ebottom are found (especially useful for semi-core states)
Figure 7.1:
Schematic dependence of DOS and
ul(r,El) on the energy
|
- >>>:line 4
- is repeated ndiff times (see line 3) for each
exception. If the same l value is specified twice, local orbitals
are added to the LAPW basis. The first energy (E1) is used for
the usual LAPW's and the second energy (E2) for the LOs, which
are formed according to (see equ. 2.8):
.
Note: You may change the automatically
created input and add d- or f-local orbitals to reduce the
linearization error (e.g. in late transtition metals you could put
E3d at 0.0 and 1.0 Ry) or s, p, d, and/or f-LOs at very high
energy (e.g. 2.0 - 3.0 Ry) to better describe unoccupied states.
- >>>:lines 3 and 4
- are repeated for each non equivalent atom
- line 5:
- format (20x,i1,2f10.1)
unit-number, Emin,Emax file number from which the k-vectors in the
irreducible wedge of the Brillouin zone are read. 5 specifies the input
file itself (as shown in the example), default is 4, for which the
corresponding information is contained in case.klist
(generated by KGEN). EMIN, EMAX: energy window in which eigenvalues
shall be searched (overrides setting in case.klist
- line 6:
- format (A10,4I5,3F5.2)
name, ix,iy,iz, idv, weight, Emin, Emax
name name of k-vector (optional)
>>>: the last line must be END !!
ix,iy,iz, idv defines the k-vector in units
of
a,
b,
c,
where x= ix/idv etc.
weight of k-vector (order of group of k)
Emin, Emax energy window in which eigenvalues shall be searched; it
must be set for first k-point but can be changed for
other k-vectors; a small window saves computer time;
it is also useful to distinguish semi-core and
valence states in some analysis applications.
- >>>: line 6
- is repeated for each k-vector in the IBZ, but
Emin and Emax may be omitted after the first k point. The utility
program kgen (see section 6.4) provides a list of
such vectors (on a tetrahedral mesh) in case.klist.
- >>>: the last line
- must be END
end:lapw1
begin:lapwso
Next: LAPWSO (adds spin orbit
Up: LAPW1 (generates eigenvalues and
Previous: Dimensioning parameters
2000-04-11