spin spiral in linear chains

Message

tanveer · #1 Post by **tanveer** » Mon Jul 11, 2011 4:43 pm

Hello All,?
I have a question related to spin-spiral wave, according to the old post on VAPS_forums, if you want to calculate the spiral spin-densty wave, you have to compile the vasp QSPIRAL flag, so i complied it. After this i have run a example of Fe linear wire by using the INCAR, POSAR and OUTCAR (see below)
INCAR:
?SYSTEM =Fe PAW-GGA??
ICHARG = 2
ISTART = 0
INIWAV = 1
VOSKOWN = 1

LNONCOLLINEAR= .TRUE.
ISPIN = 2
MAGMOM = 0.0? 0.0 3.0
LSPIRAL ? = .TRUE.
LASPH = .TRUE.
QSPIRAL = 0.0 0.0? 0.0

IBRION = 2
NSW = 100
NELM = 100
NELMDL = -6

EDIFF = 0.1E-04
EDIFFG = -.1E-02
PREC = Acc
ENCUT = 500

ISMEAR = 0
SIGMA = 0.02
NBANDS = 20
RWIGS= 1.302
LORBIT = 11
ALGO = Fast
NPAR = 1
NSIM = 1
-------poscar of? chain---------------
Fe_chain
1.00
15.00?? 0.00 ?? 0.00
0.00? 15.00??? 0.00
0.00?? 0.00???? 2.25
1
Selective dynamics
Direct
0.500 0.500 0.500 F F F
_______________________________________
In the OUTCAR, i found the?magnetization in x y and z direction:?
magnetization (x)
# of ion s p d tot
----------------------------------------
1 0.003 0.000 0.002 0.005
magnetization (y)

# of ion s p d tot
----------------------------------------
1 0.005 0.000 0.011 0.016
magnetization (z)

# of ion s p d tot
----------------------------------------
1 -0.001 0.000 0.033 0.032

the results seem inconsistent because in ferromagnetic case the magnetization should be only in z-direction.
I have also computed some calculations with different values of?QSPIRAL, such as
QSPIRAL = 0.0 0.0 0.00 (FM)
QSPIRAL = 0.0 0.0 0.25 (with 90 angle)
QSPIRAL = 0.0 0.0 0.50 (AF)
(I have propagation vector only in z-direction)
I have run these calculations so many time by changing the parameters related to the spin-spiral,but i didn?t get any correct results.
Could anybody tell me what is the problem with my calculations??
Thanks in advance,

<span class='smallblacktext'>[ Edited ]</span>

tanveer · #2 Post by **tanveer** » Mon Jul 11, 2011 4:52 pm

[quote author=Fe PAW-GGA??
ICHARG = 2
ISTART = 0
INIWAV = 1
VOSKOWN = 1

LNONCOLLINEAR= .TRUE.
ISPIN = 2
MAGMOM = 0.0? 0.0 3.0
LSPIRAL ? = .TRUE.
LASPH = .TRUE.
QSPIRAL = 0.0 0.0? 0.0

IBRION = 2
NSW = 100
NELM = 100
NELMDL = -6

EDIFF = 0.1E-04
EDIFFG = -.1E-02
PREC = Acc
ENCUT = 500

ISMEAR = 0
SIGMA = 0.02
NBANDS = 20
RWIGS= 1.302
LORBIT = 11
ALGO = Fast
NPAR = 1
NSIM = 1
-------poscar of? chain---------------
Fe_chain
1.00
15.00 0.00 0.00
0.00 15.00 0.00
0.00 0.00 2.25
1
Selective dynamics
Direct
0.500 0.500 0.500 F F F
_______________________________________
In the OUTCAR, i found the?magnetization in x y and z direction:?
magnetization (x)
# of ion s p d tot
----------------------------------------
1 0.003 0.000 0.002 0.005
magnetization (y)

# of ion s p d tot
----------------------------------------
1 0.005 0.000 0.011 0.016
magnetization (z)

# of ion s p d tot
----------------------------------------
1 -0.001 0.000 0.033 0.032

the results seem inconsistent because in ferromagnetic case the magnetization should be only in z-direction.
I have also computed some calculations with different values of?QSPIRAL, such as
QSPIRAL = 0.0 0.0 0.00 (FM)
QSPIRAL = 0.0 0.0 0.25 (with 90 angle)
QSPIRAL = 0.0 0.0 0.50 (AF)
(I have propagation vector only in z-direction)
I have run these calculations so many time by changing the parameters related to the spin-spiral,but i didn?t get any correct results.
Could anybody tell me what is the problem with my calculations??
Thanks in advance,

[/quote]