[QE-users] Problem with generating q-points for lambda

[Arena Konta]

Hello,

I try to do el-ph calculations for noncentrosymmetric compounds (  tetragonal BaNiSn3-type crystal structure, with space group I4mm (no. 107)) using QE 6.2.1: 
 
The calculations ph.x for q = 4 4 4 look follow:
 
bravais-lattice index     =            7
celldm(1)=    7.90529  celldm(2)=    0.00000  celldm(3)=    2.36005
 
 Dynamical matrices for ( 4, 4, 4)  uniform grid of q-points
 (  13 q-points):
       N         xq(1)         xq(2)         xq(3)
       1   0.000000000   0.000000000   0.000000000
       2  -0.250000000   0.000000000   0.105929929
       3   0.500000000   0.000000000  -0.211859857
       4  -0.250000000   0.250000000   0.211859857
       5   0.500000000   0.250000000  -0.105929929
       6   0.250000000   0.250000000   0.000000000
       7   0.500000000  -0.500000000  -0.423719715
       8   0.000000000   0.000000000   0.211859857
       9   0.750000000   0.000000000  -0.105929929
      10   0.500000000   0.000000000   0.000000000
      11   0.750000000  -0.750000000  -0.423719715
      12   0.500000000  -0.500000000  -0.211859857
      13   0.000000000   0.000000000  -0.423719715
 
 
The DOS and q-freq are OK. Then I need to generate q-points for lambda.in.  Using kpoints.x program I get:
      
     bravais lattice  >> 7
     filout [mesh_k]  >> Mesh
     enter celldm(3)  >> 2.36005
     mesh: n1 n2 n3   >> 4 4 4
     mesh: k1 k2 k3 (0 no shift, 1 shifted) >> 0 0 0
     write all k? [f] >>
 
     # of k-points   ==    13  of    64
    13
    1   0.0000000  0.0000000  0.0000000   1.00
    2   0.2500000 -0.2500000  0.0000000   4.00
    3   0.5000000 -0.5000000  0.0000000   2.00
    4   0.0000000  0.2500000  0.1059300   8.00
    5   0.5000000 -0.2500000  0.1059300  16.00
    6   0.0000000  0.5000000  0.2118599   4.00
    7   0.2500000  0.2500000  0.2118599   8.00
    8   0.0000000  0.0000000  0.2118599   2.00
    9   0.5000000 -0.5000000  0.2118599   2.00
   10   0.0000000  0.2500000  0.3177899   8.00
   11   0.0000000  0.5000000  0.4237198   4.00
   12   0.2500000  0.2500000  0.4237198   4.00
   13   0.0000000  0.0000000  0.4237198   1.00
 
Question: 
(1) why the q-points are not the same (at least in the same order?
(2) how to guess weight of q-points from the output ph.x ?
      
 Thank you for any help


-- 
with regards
 
Arena Konta
The Institute of Thermophysics in Novosibirsk Scientific Center