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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$\ne$ 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): $u_{E_1} + \dot
u_{E_1} + u_{E_2}$.
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 $2\pi/a$a, $2\pi/b$b, $2\pi/c$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 up previous contents
Next: LAPWSO (adds spin orbit Up: LAPW1 (generates eigenvalues and Previous: Dimensioning parameters

2000-04-11