[Pw_forum] Quick question on coordinates

Miguel Marti­nez miguel.martinez at ehu.es
Tue Feb 26 19:55:18 CET 2008

Dear colleages,

I'm currently doing some stuff on face-centered monoclinic structures, and 
have found silly problems. For example, the documentation reads:


   monoclinic (p)
      a1 = (a,0,0), a2= (b*sin(gamma), b*cos(gamma), 0),  a3 = (0, 0, c)
   where gamma is the angle between axis a and b

   base centered monoclinic
      a1 = (  a/2,         0,                -c/2),
      a2 = (b*cos(gamma), b*sin(gamma), 0),
      a3 = (  a/2,         0,                  c/2),

¿Is it right? ¿Is it a typo? I fear it's a typo, because changing ibrav 
from 12 to 13 decreases cell volume by exactly a factor of 2. What's more,
while according to the basis in the monoclinic case we'd have

Thanks in advance,


Miguel Martínez Canales
    Dto. Física de la Materia Condensada
    Facultad de Ciencia y Tecnología
    Apdo. 644
    48080 Bilbao (Spain)
Fax:  +34 94 601 3500
Tlf:  +34 94 601 5326

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