[Pw_forum] ibrav=12

[Eyvaz Isaev]

Dear Paul,

In fact, I am working on this problem in order to support in PlotPhon almost all 
lattice types. I will let you know soon, hopefully.

 
Best regards,
Eyvaz.
-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, 
Sweden 

Theoretical Physics Department, Moscow State Institute of Steel & Alloys, 
Russia, 

isaev at ifm.liu.se, eyvaz_isaev at yahoo.com




________________________________
From: W2AGZ <w2agz at w2agz.com>
To: pw_forum at pwscf.org
Sent: Fri, February 18, 2011 10:06:08 AM
Subject: [Pw_forum] ibrav=12


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
www.w2agz.com
 
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 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 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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