[Wien] Two questions on Monoclinic lattice

[Jyoti]

Dear Prof. Blaha and all Wien users,

         I am trying to do calculations in which, I need to calculate the energy of a  body centered monoclinic  system in which the non 90 degree  angle between a and b is 89.88 (a=b=c), but since there is no body centered  bravais lattice, I convert it to base centered monoclinic  system by taking ‘a’ as  the length of 110 vector and ‘b’ and ‘c’ as that of the original system, accordingly the angle between  the a and  b vectors  i.e. gamma is now half of the 89.88 i.e. 44.94. Also centered atom is between ‘a ‘and ‘c’ vectors i.e a CXZ monoclinic with gamma other than 90. I am thus able to run this system with latest WIEN2k code. In sgroup output of this calculation, it is given  that ‘unique axis is C and cell choice 2’ The manual also recommends a CXZ monoclinic only, Table 4.4 on p.39.  But however, on p.76 of the manual it was recommended to read README in SRC_sgroup, where it says that --- for monoclinic lattice only unique axis ‘c’ and cell!
  choice 1 are implemented. On the 2nd page it says that output is restricted to A centered in monoclinic. My two doubts here are,

Q1. In standard crystallography book, the nomenclature is; when the unique axis is C, the lattice can be A or B centered, which is called 1st setting. When the unique axis is b the lattice can be A or C centered, which is called 2nd setting. So I am not clear what is meant by cell choice 1 in README, does it mean the 1st setting ? and if so,
Q2. Whether the smooth running of my calculation, in which the system is B centered (and not A centred) and sgroup output says ‘ unique axis is c and cell choice is 2’ (and not the cell choice 1) is in error as I am getting its energy correctly, i.e. close to the bcc system where the gamma angle is 90 and not 89.88.
                         I would be very thankful and appreciate very much if anyone could please clarify me about these nomenclatures and related two questions.
Thanks,
Jyoti 


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