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Hello all,
I'm attempting a calculation with a large number of atoms (162) and trying to set the MAGMOM keyword. I'm setting this to:

MAGMOM = 4 0 0 0 0 0 0 0 0 0 0 0 0 etc....

I'm basically trying to induce an excess charge on atom 1 compared to the rest.

Unfortunately, when I try this, it fails and gives the following in the log file:

vasp.4.6.28 25Jul05 complex
POSCAR found : 2 types and 162 ions
Error reading item 'MAGMOM' from file INCAR.
Error code was IERR=0 ... . Found N= 123 data.

I've tried this calculation with a smaller number of atoms and it works fine. I've also tried this large calculation on different machines with the same error, so I feel there is a problem with VASP. I'm guessing that there is a limit (~132) to the number of characters on a line that VASP can read.

How can I get around this limitation?

Thank you,

Aaron

From a standard compilation MAGMOM is limited to 255 characters.
If you need a longer input you have to:
-) write in the vasp.4.lib library in file drdatab.F
#define LONGCHAR
at the beginning, befor #ifdef LONGCHAR, and
-) recompile the library

Thanks -that works great.

Aaron

Or, more simply as I recently confirmed in this forum, you can write it in the format (number of atoms)*moment, in your example
MAGMOM = 4 0 0 0 0 0 0 0 0 0 0 0 0 etc....
can be written as
MAGMOM=4 158*0
<span class='smallblacktext'>[ Edited Thu Mar 16 2006, 06:16PM ]</span>

Hello all,
I'm trying to make a non collinear calculation but i have a problem with the MAGMOM tag. I tried to modify the drdatab.F and compile again but the problem is still there.... (I tried also to specify the mag moment for each atom)
This is the error message:

running on 2 nodes
distr: one band on 1 nodes, 2 groups
vasp.4.6.3 06Feb03 complex
POSCAR found : 4 types and 50 ions
Error reading item 'MAGMOM' from file INCAR.
Error code was IERR=0 ... . Found N= 74 data.

this is my incar:

system = YBCO 6.5 bulk PAW
NELM = 40
NELMIN = 5
NWRITE = 2
ISTART = 0
EDIFF = 1.E-04
EDIFFG = -1.E-02
NSW = 0
IBRION = -1
ISIF = 2
ISMEAR = 1
LREAL= .TRUE.
PREC = High
ENCUT = 400
SIGMA = .2
ALGO = FAST
# Conto non collineare
ICHARG = 1
LNONCOLLINEAR= .TRUE.
ISPIN = 2
MAGMOM = 4*0 8*0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 -1 1 0 1 -1 0 1 0 0 -1 0 0 0 1 0 0 -1 1 0 0 26*0
#

Could you help me?
thank you in advance

Mauro

When you're doing non-collinear calculations you have to specify a vector for each atom, i.e. three entries per atom. So if you have 50 ions you therefore will have to have 150 elements on the MAGMOM-line. In this file you only have 74 entries and therefore you also get an error.

Best regards,
/Dan

I tried also with three components for each atom, but the error message is the same...


running on 2 nodes
distr: one band on 1 nodes, 2 groups
vasp.4.6.3 06Feb03 complex
POSCAR found : 4 types and 50 ions
Error reading item 'MAGMOM' from file INCAR.
Error code was IERR=0 ... . Found N= 35 data.


my INCAR:

MAGMOM = 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 -1 1 0 1 -1 0 1 0 0 -1 0 0 0 1 0 0 -1 1 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

It appears you using row breaks at the MAGMOM line so that it just reads the first line (which contains 35 entries). Try to put all entries on the same line. If you want that specific configuration you can write:

MAGMOM = 48*0 -1 0 0 0 -1 1 0 1 -1 0 1 0 0 -1 0 0 0 1 0 0 -1 1 80*0

Best regards,
/Dan

<span class='smallblacktext'>[ Edited Mon Feb 18 2008, 02:39PM ]</span>

it seems to work!
Thank you very very much.
best regards
Mauro

hello all,
I have the same problem: too long string in INCAR for the MAGMOM-tag
is it possible to write something like 4*0 but for triplets
i mean is it possible to write something like 3*(0 0 1 ) instead of 0 0 1 0 0 1 0 0 1 ?
thank you all

From a standard compilation MAGMOM is limited to 255 characters.
[ Edited Mon Nov 14 2011, 01:16PM ]

Hi,
I am attempting to compile VASP 5.2 with the MAGMOM-tag not limited to 255 Characters. I am unable to locate "#ifdef LONGCHAR" in the drdatab.F file. Is the method different for compiling VASP 5.2? Thanks in advance.

*** Yes, The procedure is the same as VASP 4.6.
<span class='smallblacktext'>[ Edited Tue Oct 09 2012, 05:32PM ]</span>

is there any specified step to compile the limitations?
Thank you very much!