[Wannier] Unable_to_satisfy_B1

[Satyananda Chab]

Dear experts & developers,

I am working on a monolayer transition-metal trichalcogenide semiconductor
with a vacuum of about 20 \AA in the z-direction and I am trying to get MLWF
for the same. However the code throws the following error saying that it is
unable to satisfy B1 with any of the first  12 shells. I try changing the
search_shells
parameters in the .win file as suggested by the code which does not help. I
try
changing the tolerance which also goes in vain. I request the experts and
developers
in this forum to point out the probable reason(s) for the error. Help
acknowledge
thankfully in advance.


                satya


                                ------------
                                K-POINT GRID
                                ------------

             Grid size = 11 x 11 x  1      Total points =  121

*---------------------------------- MAIN
------------------------------------*
 |  Number of Wannier Functions               :
48             |
 |  Number of input Bloch states              :
48             |
 |  Output verbosity (1=low, 5=high)          :
1             |
 |  Timing Level (1=low, 5=high)              :
1             |
 |  Optimisation (0=memory, 3=speed)          :
3             |
 |  Length Unit                               :
Ang             |
 |  Post-processing setup (write *.nnkp)      :
F             |
 |  Using Gamma-only branch of algorithms     :
F             |
 *----------------------------------------------------------------------------*
 *------------------------------- WANNIERISE
---------------------------------*
 |  Total number of iterations                :
100             |
 |  Number of CG steps before reset           :
5             |
 |  Trial step length for line search         :
2.000             |
 |  Convergence tolerence                     :
0.100E-09             |
 |  Convergence window                        :
-1             |
 |  Iterations between writing output         :
1             |
 |  Iterations between backing up to disk     :
100             |
 |  Write r^2_nm to file                      :
F             |
 |  Write xyz WF centres to file              :
F             |
 |  Use guiding centre to control phases      :
F             |
 *----------------------------------------------------------------------------*
 Time to read parameters        0.004 (sec)

 *---------------------------------- K-MESH
----------------------------------*
 +----------------------------------------------------------------------------+
 |                    Distance to Nearest-Neighbour
Shells                    |
 |
------------------------------------                    |
 |          Shell             Distance (Ang^-1)
Multiplicity         |
 |          -----             -----------------
------------         |
 |             1                   0.096882
2            |
 |             2                   0.096887
4            |
 |             3                   0.167807
4            |
 |             4                   0.167815
2            |
 |             5                   0.193764
2            |
 |             6                   0.193773
4            |
 |             7                   0.256327
4            |
 |             8                   0.256332
4            |
 |             9                   0.256341
4            |
 |            10                   0.279157
2            |
 |            11                   0.290645
2            |
 |            12                   0.290660
4            |
 +----------------------------------------------------------------------------+
 | The b-vectors are chosen
automatically                                     |
 | SVD found small singular value, Rejecting this shell and trying the
next   |
 | SVD found small singular value, Rejecting this shell and trying the
next   |
 | SVD found small singular value, Rejecting this shell and trying the
next   |
 | SVD found small singular value, Rejecting this shell and trying the
next   |
 | SVD found small singular value, Rejecting this shell and trying the
next   |

 Unable to satisfy B1 with any of the first  12 shells
 Your cell might be very long, or you may have an irregular MP grid
 Try increasing the parameter search_shells in the win file (default=12)

 Exiting.......
 kmesh_get_automatic


-- 
Satyananda Chabungbam
PostDoc Fellow
Harish-Chandra Research Institute
Allahabad-211019
India
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