pymatgen.io.vasp.inputs.Incar() does not readd the full MAGMOMS when they are split on multiple lines

[michelegalasso]

Python version

3.13.7

Pymatgen version

2025.10.7

Operating system version

Ubuntu 25.10

Current behavior

My INCAR has the following MAGMOM tag:
MAGMOM = 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5.0 0.0 0.0 5.0 0.0 0.0 5.0 0.0 0.0 -5.0 0.0 0.0 -5.0 0.0 0.0 -5.0
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 0.0 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 0.0 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 0.0
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

With this code:
incar = pymatgen.io.vasp.inputs.Incar("INCAR")
print(incar.get("MAGMOM"))

I get:
[[0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 5.0], [0.0, 0.0, 5.0], [0.0, 0.0, 5.0], [0.0, 0.0, -5.0], [0.0, 0.0, -5.0], [0.0, 0.0, -5.0]]

Expected Behavior

I should get:
[[0.0, 0.0, 0.0], [0.0, 0.0, 0.0], [0.0, 0.0, 5.0], [0.0, 0.0, 5.0], [0.0, 0.0, 5.0], [0.0, 0.0, -5.0], [0.0, 0.0, -5.0], [0.0, 0.0, -5.0],
[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], [0.0, 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, 0.0, 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, 0.0],
[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]]

Minimal example

Relevant files to reproduce this bug

No response

[DanielYang59]

I'm not sure if this is a valid way to split a long line, as per VASP Wiki you should have backslash:

For better readability, long lines can be split with a backslash \ . Avoid blanks after the backslash because some versions of VASP cannot parse those. For instance,

MAGMOM  = 0 0 1.0 0 0 -1.0 \
            0 0 1.0 0 0 -1.0 \
            6*0

[michelegalasso]

Sorry, the backslash did not get pasted, but I have it in my INCAR. I do split lines with backslashes and Pymatgen reads only the first one.

[DanielYang59]

emmm I see the fix was not yet included in the latest 2025.10.7 release, can you try the master branch and see if it fixed?

• Enhance INCAR parsing: handle multi-line string and line continuation with backslash, fix handling of ! as comment marker #4518

[DanielYang59]

BTW the following is not the correct usage (init method wouldn't take filename):

incar = pymatgen.io.vasp.inputs.Incar("INCAR")
print(incar.get("MAGMOM"))

You should use something like this instead:

from pymatgen.io.vasp.inputs import Incar

incar = Incar.from_file("INCAR")
print(incar.get("MAGMOM"))

[michelegalasso]

Yes, with master it works. Thanks! Looking forward to the new release! :)