[Pw_forum] ibrav=12

W2AGZ w2agz at w2agz.com
Fri Feb 18 20:43:14 CET 2011

Thanks, Eyvaz.  The space group I’m interested in is P21/c  (14).  8 atoms per unit cell, 24 IRs.  If you need a beta tester, just ask.  -Paul


From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On Behalf Of Eyvaz Isaev
Sent: Friday, February 18, 2011 9:05 AM
To: PWSCF Forum
Subject: Re: [Pw_forum] ibrav=12


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,

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



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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