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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