WIEN2k tips

WIEN2k tips (WIEN2k workshop 2015 Q&A )
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http://www.wien2k.at/events/ws2015/
http://www.wien2k.at/reg_user/faq/
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■ Isolated oxygen calculation (Cohesive energy needs it)

◇ general setting
  • FCC
  • a, b, c = 30.0, 30.1, 30.2 bohr <-  to resolve a degeneracy
  • 1 k-point
  • spinploraized calculation

◇ case.in2 (isolated oxygen successfully run)
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TOT             (TOT,FOR,QTL,EFG,FERMI)
  -12.00    6.00   0.50 0.05  1   EMIN, NE, ESEPERMIN, ESEPER0, iqtlsave
TEMP    0.002      (GAUSS,ROOT,TEMP,TETRA,ALL      eval)
  0 0  2 0  2 2  4 0  4 2  4 4  6 0  6 2  6 4  6 6
 12.00          GMAX
NOFILE        FILE/NOFILE  write recprlist
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◇ treatments for error
1. QLT-B error
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EF in case.scf2up -> EF in case.in1
all orbital in case.in1-> EF -0.2 in case.in1
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2. co-worker say "deduce RMT."

◇ example (Isolated oxygen calculation)
□ structure generation
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View only mode -->edit STRUCT file

Title: 
Lattice:
Type: F
Spacegroups from
Bilbao Cryst Server
Lattice parameters in
       a= b= c=
       α= β= γ=

Inequivalent Atoms: 1
Atom 1: Z= RMT=
       Pos 1: x= y= z=
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□ fast mode
select spin-polarized calculation
RMT reduction by X % (default: RMT not changed)
VXC option (13=PBE, 5=LDA, 11=WC, 19=PBEsol) [default=13]
energy seperation between core/valence (default: -6.0 Ry)
RKMAX (default: 7.0) Click here for more info)
use TEMP with smearing by X Ry (default: TETRA)
use X k-points in full BZ (default: 1000; Click here for more info)
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□ case.in1
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WFFIL  EF=-.390264287975   (WFFIL, WFPRI, ENFIL, SUPWF)
 4       10    4 (R-MT*K-MAX; MAX L IN WF, V-NMT
 -0.90    3  0      (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global APW/LAPW)
 0   -1.75      0.002 CONT 1
 0   -0.90      0.000 CONT 1
 1   -0.90      0.000 CONT 1
K-VECTORS FROM UNIT:4   -9.0       1.5    17   emin / de (emax=Ef+de) / nband
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Note: ( QLT-B error (EF in case.scf2up -> EF in case.in1, all orbital in case.in1 -> EF -0.2 in case.in1 ))

□ fast mode (once again)
select spin-polarized calculation
RMT reduction by X % (default: RMT not changed)
VXC option (13=PBE, 5=LDA, 11=WC, 19=PBEsol) [default=13]
energy seperation between core/valence (default: -6.0 Ry)
RKMAX (default: 7.0) Click here for more info)
use TEMP with smearing by X Ry (default: TETRA)
use X k-points in full BZ (default: 1000; Click here for more info)
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□ results ( 1 cycle / 2 min.)
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>   stop

:CHARGE convergence:  1 0.001 -.0000039
:ENERGY convergence:  1 0.001 .0000226500000000
>   mixer   	(13:04:12) 0.671u 0.092s 0:00.76 100.0%	0+0k 0+10232io 0pf+0w
>   lcore -dn	(13:04:12) 0.012u 0.008s 0:00.02 50.0%	0+0k 0+144io 0pf+0w
>   lcore -up	(13:04:12) 0.016u 0.004s 0:00.02 50.0%	0+0k 0+136io 0pf+0w
>   lapw2 -dn       	(13:04:10) 1.549u 0.040s 0:01.59 99.3%	0+0k 0+6136io 0pf+0w
>   lapw2 -up       	(13:04:08) 1.854u 0.056s 0:01.91 99.4%	0+0k 0+6136io 0pf+0w
>   lapw1  -dn      	(13:04:07) 0.872u 0.032s 0:00.90 100.0%	0+0k 0+1400io 0pf+0w
>   lapw1  -up      	(13:04:06) 1.065u 0.028s 0:01.09 99.0%	0+0k 0+1408io 0pf+0w
>   lapw0 	(13:03:06) 58.927u 0.616s 0:59.52 100.0%	0+0k 0+6504io 0pf+0w

    cycle 19 	(Fri Jun 26 13:03:06 SGT 2015) 	(22/81 to go)

:CHARGE convergence:  0 0.001 .0073864
:ENERGY convergence:  1 0.001 .0009363450000000
>   mixer   	(13:03:05) 0.675u 0.068s 0:00.74 98.6%	0+0k 0+10232io 0pf+0w
>   lcore -dn	(13:03:05) 0.020u 0.000s 0:00.02 100.0%	0+0k 0+136io 0pf+0w
>   lcore -up	(13:03:05) 0.020u 0.000s 0:00.02 100.0%	0+0k 0+136io 0pf+0w
>   lapw2 -dn       	(13:03:02) 2.078u 0.060s 0:02.14 99.5%	0+0k 0+6144io 0pf+0w
>   lapw2 -up       	(13:03:00) 2.043u 0.068s 0:02.13 98.5%	0+0k 0+6136io 0pf+0w
>   lapw1  -dn      	(13:02:59) 1.072u 0.024s 0:01.10 99.0%	0+0k 0+1408io 0pf+0w
>   lapw1  -up      	(13:02:58) 0.870u 0.044s 0:00.92 98.9%	0+0k 0+1400io 0pf+0w
>   lapw0 	(13:01:59) 58.024u 0.692s 0:58.69 100.0%	0+0k 0+6504io 0pf+0w

    cycle 18 	(Fri Jun 26 13:01:59 SGT 2015) 	(23/82 to go)
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■ WIEN2k lattice
WIEN2k automatically change lattice structure.
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input: conventional lattice
scf: primitive lattice
output: conventional lattice
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■ Automatic determination of RMTs
RMT of A in new is larger than old scheme one.
RMT of B in new is smaller than old scheme one.
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example
new: RMT(A atom) 2.2, RMT(B atom) 1.5
old: RMT(A atom) 1.9, RMT(B atom) 1.8
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new: fast scf calculation, but bit unsafety.
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■ save memory and mandaitly
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1. usual scf calculation
  RKmax 5, small k point
2. lstart
  -6 Ry -> -3 Ry
3. RKmax 7
4. small k point -> many k point
5. run SCF
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Note 1: you chainging lstart from -6 Ry to -3 Ry, WIEN2k automatically change case.inc ( core and semicore:T, valence:F) and case.in1. Its scf calulation speed is slow or maginally fast.
Note 2: Positive value in lstart:separate semicore and core by q/sphere.
Note 3: cputime
Basis set scales with RKmax^3
cputime scales with Npw^3
increasing RKmax by 10% -> doubles cputime
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■ case.in1
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principal number is different at same orbit and atom in case.in1.
FE=0.500  is changed by every scf cycle. (refine)
0 0.3 0.000 CONT 1 Es <- 3p
0 -3.72 0.005 STOP 1 Es-LO <- 2p
(Start El energy equal -3.72 Ry)
(STOP prevent orbital (for example, unoccupied state) being infinite energy.)
valence -6 Ry > semicore -9 Ry > core
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■ RKmax
Maximum of RKmax is 12, because of its linear dependency.
Overcompleteness
 
■ AFM calculation
afminput
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Cr1 (0, 0, 0)
Cr2 (1/2, 1/2, 1/2)
 
identity + (1/2, 1/2, 1/2)
identity = (1/2, 0, 0), (0, 1/2, 0) or (0, 0, 1/2).
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■ structure optimization
PORT2.0
0.0 x y z <- 0.0 = constrain

■ Work function (WF)
case.scf
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:FER <- vacuume
:VZERO <- solid
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Note: WF = :VZERO - :FER
 
■ GW calculation code
FHI-gap for WIEN2
 
■ SOC
◇ case.outsmso -> pointgroup, e.g. 4/mmm 
◇ xcysden have primitive cell mode
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2nd line B, F, H, P, etc in case.struct link xcrysden, wien2k and octave.
(you changing B -> P, remove (1/2, 1/2, 1/2) from atomic positions.)
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◇ symmetry operation
□ relationship: Symmetry operations in case.sturcut relate "International Tables Vol. A." and bilbao crystallographic server: http://www.cryst.ehu.es/.
□ change space group ( [001] magnetic direction )
No.197(I23) -> SOC -> structs_so -> http://www.cryst.ehu.es/cryst/maxsub.html -> Transformed 23(I222) + (1/2, 1/2, 1/2) (2nd line B in case.struct)
No.197(I23) -> SOC -> structs_so ->  http://www.cryst.ehu.es/cgi-bin/cryst/programs/checkgr.pl?tipog=gesp -> 16(P222) (2nd line P in case.struct)

◇ symmetry operation for SOC calc.
A -> keep
B -> keep (time inversion symmetry exist) or remove
C -> remove
(C type change magnetization direction)
 
symmetso: This program helps to setup spin-orbit itcalculations in magnetic systems. Since SO may break symmetry in certain spacegroups, it classifies your symmetry operations into operations A , which do not invert the magnetization (identity, inversion, rotations with the rotation axis parallel to magnetization), B, which invert it (mirror planes) and C , which change the magnetization in some other way. (Note: magnetization is a result of a circular current, or equivalently, an axial vector resulting from a vector product . symmetso will keep all A-type and throw away all C-type symmetry operations. Depending on the presence of inversion symmetry it will keep (inversion is present) or remove the B-type operations. Finally, symmetso uses the remaining symmetry operations to check/generate equivalent atomic positions (it can happen that some equivalent atoms become non-equivalent after inclusion of SO interaction).
 
◇ symmetso (messages)
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 gamma not equal 90
 gamma not equal 90
   gamma not equal 90
   gamma not equal 90
 gamma not equal 90
 gamma not equal 90
 gamma not equal 90
 alpha(3) .gt. 91.0; reset to 90.1
0.448u 0.032s 0:00.48 97.9%	0+0k 0+9088io 0pf+0w

Ignoring above message is OK !
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◇ P1/2 LO (heavy elements) including condition
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EF
Valence: hybridized orbital region <- not include P1/2
Valence: almost isolated P1/2 orbital <- include P1/2
semi-core: T in case.inc
core: T in case.inc
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■ DFT+U
AMF: metal
SIC: no metal
HMF: fast scf calculation speed, but not recommend
When you set same Ueffect, its relationship is gap(AMF) < gap(SIC).

■ octave (free soft, support WEIN2k struct file)
◇ basic run
octave
s=loadstruct("*.struct") <- (s is structure variable)
showstruct(s) <- xcrysden run
help makesupercell
a=[1 1 0; -1 1 0; 005]
ss=makesupercell(sc.a)
savestruct(ss, "test.struct")
exit
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Note: script adress (SRC_structediter/bin)

◇ help
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helpstruct
help slabs
help mergestruct
help rotate
help rotateatomlist
help rescale_c(ss.70)
etc
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◇ information
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s.a <- show lattice constant
s.pos <- show postion
s.aname <- show atomic nam
s.alpha
s.bralt
ssur=makesurface(ss,n,1,z,20.0)
ssur1=makesurface(ss,n,1,z/2,20.0)
slabs=slabs(ssur, ssur1)
etc
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◇ IDOS (maybe Tetrahedron method)
see outputt, outputtup or outputtdn
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