[Pw_forum] ibrav=12

W2AGZ w2agz at w2agz.com
Fri Feb 18 08:06:08 CET 2011

To All (especially Eyvaz):


I would like to create a file for PlotPhon/Include to support general
monoclinic structures.  Below is the Include file for orthorhombic as an
example "kick off:"


# Simple Orthorhombic lattice (X=b/a, Y=c/a)

  1.0  0.0       0

  0.0  XX        0

  0.0  0.0       YY

# With respect to basis vectors

1   0.00000  0.00000   0.50000    Z

50  0.00000  0.00000   0.00000    G

50  0.500000 0.00000   0.00000    X

50  0.500000 0.50000   0.00000    S

50  0.000000 0.50000   0.00000    Y

50  0.000000 0.00000   0.00000    G

50  0.500000 0.50000   0.50000    R


Now, the "popular" cell convention for monoclinic structures is either
"b-axis-unique," or "c-axis-unique."  PWgui and PWscf prefer the latter, but
that's OK, since it's a simple transformation, as least in direct space,
between the two.  But, what is the appropiate "include" for ibrav=12 "c-axis
unique?"  I've been to "BILBOA," and the Bouchaert-Smoluchowski-Wigner path
I want is gamma-a-u-e-z-lambda-gamma for both electrons and phonons.
Incidentally, when I was a graduate student, the legend was that the BSW
notation was invented by physicists to purposely confuse chemists.  So,
please tell me how to construct the appropriate "scripts/lines" and
"include" files accordingly.


Grazi, Paul Grant

IBM Research Staff Member Emeritus



Addenda...I include the following at the risk of angering Santo Paolo who
may excommunicate me from the forum on the basis of "topic out of bounds."
"Mea culpa...dominus noster..."  Therefore I apologize for this posting and
to those for whom English is not their native language, especially
Americans, Australians, Kiwis, Irish, Scots, Welsh, Cornish, Indians and
particularly Quebecois (British Columbians excepted).


2011 is the 100th anniversary of the discovery of superconductivity and the
25th of above liquid nitrogen in copper oxide perovskites.  I will be giving
one of the plenary talks at the upcoming APS March Meeting in Dallas...go
here <http://meetings.aps.org/Meeting/MAR11/APS_epitome>  for the epitome.
And later a reprise at the MRS April Meeting in San Francisco.  But, in
addition, I will also present a contributed talk at each meeting on "proxy"
CuO structures based entirely on Quantum Espresso resources...go here
<http://meetings.aps.org/Meeting/MAR11/Event/139995>  to see.


I would love to see and meet members of the QE community at each event...and
offer a "real espresso" beverage.   Look for me outside any of the
superconductivity sessions, or inquire in the press room.  I'm reasonably
identifiable...an old guy with long white hair and beard.
Hmm...well...maybe not that unique!


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