[Pw_forum] Using a big box model to calculating the energy of isolated atom.

[Hongsheng Zhao]

Hi all,

I've learned that when using the a large-cell ( i.e., a big box ) to 
calculate the energy of isolated atom, it should be done without 
symmetry.   But I'm not sure what's the meaning of the  "without 
symmetry"  here and how to ensure this when we using a a big box model 
for this purpose.  Any hints on this issue?

Regards
-- 
Hongsheng Zhao <zhaohscas at yahoo.com.cn>
School of Physics and Electrical Information Science,
Ningxia University, Yinchuan 750021, China