 
#################################################### 
#       SiO2   alpha cristobalite                  #
####################################################



     Nabil      |                | All elec.   |  All elec       | 
    siesta-PBE  | abinit-PBE [1] | B3LYP[2]    |crystal B3LYP [3]|   EXP [4]
-------------------------------------------------------------------------------
Kpoint   6*6*6  |   4*4*4        |     6-8     |    18           |

cell parameters
----------------
a(A)| 4.99397  |    5.0730       |  4.989     |   5.0285       | 4.9836 
c(A)| 6.93604  |    7.0852       |  6.902     |   7.0125       | 6.9549

atomic fractonal coordinates
----------------------------
Six  | 0.3051  |   0.3001        |  0.3069     |   0.2992       | 0.3057
Siy  | 0.3051  |   0.3001        |  0.3069     |   0.2992       | 0.3057
Siz  | 1.0000  |   1.0000        |  1.0000     |   1.0000       | 1.0000 

Ox   | 0.2363  |  0.2384         |  0.2362     |   0.2396       | 0.2513
Oy   | 0.1177  |  0.1081         |  0.1188     |   0.1039       | 0.0952
Oz   | 0.1865  |  0.1819         |  0.1866     |   0.1784       | 0.1561



Ref:
----

[1]Sinisa Coh and David Vanderbilt,Phys Rev B 78, 054117 (2008)
[2]M. Catti,B. Civalleri,and P. Uglieng; J. Phys. Chem. B, 104 (31), 7259-7265, (2000)
[3]Ben Yahia M., Orhan E.; J. of Phys. Chem. B 112  10777-10781 ,(2008)
[4]Kim Yong-Il et al Journal of Liminescence, 115, 1-6 (2005)

  
With Siesta, and 4 x 4 x 4, 
outcell: Cell vector modules (Ang)   :    4.993961    4.993941    6.936114
