[Pw_forum] Help in using xcrysden for making structures

[Neel Singh]

hi,
 I need some help in drawing crystal using xcrysden. Sir/Madam, let us take the case of FCC for which ibrav=2, and celldm(1)=9.000. Now if i know that i have 18 atoms in my unit cell and i know the Cartesian co-ordinates{x,y,z} of each atom in angstrom/bhor. I want to know that how can i draw my unit cell with giving positions of all the atoms without using the symmetries by xcrysden??. Means like if i specifiy,
& system
ibrav=2, celldm(1)=9.00, nat=1,......
ATOMIC POSITIONS{angstrom} 
A  0  4.5 0

now if we visualise this type of structure with Xcrysden, we found a number of atoms genrated due to symmetry. If i make a file like 
 & system

ibrav=2, celldm(1)=9.00, nat=18,......

ATOMIC POSITIONS{angstrom} 

A  0  4.5 0
/
18 times we have specified the co-ordinates
/
/
A  4.5 0 0 
Xcrysden will give warning like atom 10 and 90 are very close like that.
Sir i want to know is there any way so that i can make my PWSCF input file with angstrom/bohr postions such that with one atomic postion Xcrysden will show only one atom??
Means i will give 18 atomic postions and xcrysden will produce 18 atom unit cell without using symmatries. 

Thanks for your help,
Neel Singh,
Univeristy of Delhi,
India



      See the Web's breaking stories, chosen by people like you. Check out Yahoo! Buzz. http://in.buzz.yahoo.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090904/e7c0711c/attachment.htm