# DFT+U Calculation - Symmetry Error

**URL:** <https://discourse.abinit.org/t/dft-u-calculation-symmetry-error/3206>\
**Category:** Ground state\
**Created:** [November 9, 2022, 11:08pm UTC](https://discourse.abinit.org/t/dft-u-calculation-symmetry-error/3206 "2022-11-09T23:08:32Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![chmgrdstu](https://discourse.abinit.org/letter_avatar_proxy/v4/letter/c/a88e4f/32.png) [@chmgrdstu](https://discourse.abinit.org/u/chmgrdstu)\
**Post date:** [November 9, 2022, 11:08pm UTC](https://discourse.abinit.org/t/dft-u-calculation-symmetry-error/3206/1 "2022-11-09T23:08:32Z")

</div>

Hello!  
I’m trying to determine the Hubbard U value of Co in space group 194. I’ve been following the tutorial that the ABINIT site has, and I’ve been getting Warnings about “Trouble finding symmetrically equivalent atoms”. A sample of these warnings is:

— !WARNING  
src\_file: m\_symtk.F90  
src\_line: 1959  
message: |  
Trouble finding symmetrically equivalent atoms  
Applying inv of symm number 24 to atom number 2 of typat 1  
gives tratom= -1.0000E+00 -6.6667E-01 -7.5000E-01.  
This is further away from every atom in crystal than the allowed tolerance.  
…

The inverse symmetry matrix is -1 -1 0  
0 1 0  
0 0 -1  
and the nonsymmorphic transl. tnons = 0.0000000 0.0000000 0.0000000  
The nearest coordinate differs by 2.220E-16 1.110E-16 -5.000E-01  
for indsym(nearest atom)= 2  
symatm: maximum (delta t)= 5.00000E-01 is larger than tol= 1.0000E-08

Then it throws the following error:  
— !ERROR  
src\_file: m\_symtk.F90  
src\_line: 2014  
mpi\_rank: 0  
message: |  
Largest error (above) is so large (0.01) that either input atomic coordinates (xred)  
are wrong or space group symmetry data is wrong.  
Action: correct your input file.  
…

I’m trying to figure out what may be wrong with my input file, and as I’m a new user, I can’t upload files right now. So, below is a paste from the input file:

#Unit Cell  
acell 2.456 2.456 3.878 angstroms  
angdeg 90 90 120  
chkprim 0

```
rprim 1.0 0.0 0.0
         -0.5 0.86602540378 0.0
          0.0 0.0 1.0

```

nsppol 2

#Definition of the atom types  
ntypat 1  
znucl 27

#Definition of the atoms  
natom 2  
typat 2\*1 # atomic types  
xred

1/3 2/3 1/4  
2/2 1/3 3/4

ecut 25  
pawecutdg 60  
nband 34

#Definition of the k-point grid  
kptopt 1  
ngkpt 8 8 8  
nshiftk 1  
shiftk 0.0 0.0 0.5

#Smearing  
occopt 7  
tsmear 0.05 eV

#DFT+U  
usepawu 1  
lpawu 2  
nsym 24

```
       symrel 1 0 0 0 1 0 0 0 1	-1 0 0 0 -1 0 0 0 -1
                   0 1 0 1 0 0 0 0 1 0 -1 0 -1 0 0 0 0 -1
                   1 1 0 -1 0 0 0 0 1	-1 -1 0 1 0 0 0 0 -1
                  -1 0 0 1 1 0 0 0 1 1 0 0 -1 -1 0 0 0 -1
                   0 1 0 -1 -1 0 0 0 1 0 -1 0 1 1 0 0 0 -1
                  -1 -1 0 0 1 0 0 0 1 1 1 0 0 -1 0 0 0 -1
                  -1 0 0 0 -1 0 0 0 1 1 0 0 0 1 0 0 0 -1
                   0 -1 0 -1 0 0 0 0 1 0 1 0 1 0 0 0 0 -1
                  -1 -1 0 1 0 0 0 0 1 1 1 0 -1 0 0 0 0 -1
                   1 0 0 -1 -1 0 0 0 1	-1 0 0 1 1 0 0 0 -1
                   0 -1 0 1 1 0 0 0 1 0 1 0 -1 -1 0 0 0 -1
                   1 1 0 0 -1 0 0 0 1	-1 -1 0 0 1 0 0 0 -1

```

pawujat 1  
pawujv 0.01 eV  
macro\_uj 1

#Only to accelerate test  
irdwfk 1  
tolvrs 10d-9

#Save disk space  
prteig 0  
prtwf 0  
prtden 0

Thank you for your help!!

---

<div class="post-metadata">

**Author:** ![LucaBuia](https://discourse.abinit.org/letter_avatar_proxy/v4/letter/l/7feea3/32.png) [@LucaBuia](https://discourse.abinit.org/u/LucaBuia)\
**Post date:** [November 20, 2022, 8:44pm UTC](https://discourse.abinit.org/t/dft-u-calculation-symmetry-error/3206/2 "2022-11-20T20:44:41Z")

</div>

Hi,

I think your unit cell definition is redundant and the reduced coordinates are wrong, try using just

> #Unit Cell  
> acell 2.456 2.456 3.878 angstroms  
> angdeg 90 90 120
> 
> nsppol 2
> 
> #Definition of the atom types  
> ntypat 1  
> znucl 27
> 
> #Definition of the atoms  
> natom 2  
> typat 2\*1 # atomic types  
> xred
> 
> 1/3 2/3 1/4  
> 2/3 1/3 3/4
> 
> ecut 25  
> pawecutdg 60  
> nband 34

Luca