[Wannier] problem for hexagonal cell

[Hongwei Wang]

Dear Wannier90 users and developers：

 I get an error from wannier90 that I don't know how to fix. I am attempting to do a calculation for hexagonal
cell. 

                              Lattice Vectors (Ang)
                    a_1     5.151418  -2.974197   0.000000
                    a_2     0.000000   5.948357   0.000000
                    a_3     0.000000   0.000000  11.694322
 
                   Unit Cell Volume:     358.34296  (Ang^3)
 
                        Reciprocal-Space Vectors (Ang^-1)
                    b_1     1.219700   0.000000   0.000000
                    b_2     0.609854   1.056289   0.000000
                    b_3     0.000000   0.000000   0.537285

I got an error message after executing the command wannier 90 -pp seedname.
 
 B1 condition is not satisfied: Adding another shell
 Exiting.......
 kmesh_get_bvector: Not enough bvectors found
 +----------------------------------------------------------------------------+
 |                    Distance to Nearest-Neighbour Shells                    |
 |                    ------------------------------------                    |
 |          Shell             Distance (Ang^-1)          Multiplicity         |
 |          -----             -----------------          ------------         |
 |             1                   0.134321                      2            |
 |             2                   0.152463                      6            |
 |             3                   0.203192                     12            |
 |             4                   0.264073                      6            |
 |             5                   0.268643                      2            |
                                       .
                                       .
                                       .
 +----------------------------------------------------------------------------+
 I set the parameter kmesh_tol = 0.018143 and executed the command "wannier 90 -pp seedname"
again, however, I got another erro message:

 Exiting.......
 kmesh_get_bvector: Not enough bvectors found

 +----------------------------------------------------------------------------+
 |                    Distance to Nearest-Neighbour Shells                    |
 |                    ------------------------------------                    |
 |          Shell             Distance (Ang^-1)          Multiplicity         |
 |          -----             -----------------          ------------         |
 |             1                   0.134321                      8            |
 |             2                   0.203192                     12            |
 |             3                   0.268643                      8            |
 |             4                   0.308891                     30            |
 |             5                   0.333199                     12            |
                                       .
                                       .
                                       .
 +----------------------------------------------------------------------------+

 The smallest shell (a star of 6 vectors) is good for cubic crystal. Two shells
 (star of 4 vecors and star of 2 vector) will be a enough to describe a gradient
in tetragon cell. To satisfy B1 in a simple orthorhombic cell( a/=b/=c angles=90),
it need 3 kpoint shells, each with 2 kpoints (6 total). It has too many vecors in
the second shell to find enough bvectors for hexagonal cell, but if I don't consider
the second shell,the B1 condition will not be satisfied. I wonder if someone can give
me some suggestions to fix this problem. Thanks for any help.

Best regards

Hongwei Wang