[Pw_forum] Charge density: what min and max values represent?

[Tram Bui]

Dear Everyone,
    I have got the data below from my output of 2D charge density
calculation. I ran my work for two different defects type in bulk SiC (2x2x2
super cell):
- One defect with Cs sits at C site (1/4 1/4 1/4 position), I got this
information below
               Min, Max, imaginary charge:     0.000143    0.391420
0.000000
- One defect with Cs sits at Si site (1/2 1/2 0 position) and I got the
information below
               Min, Max, imaginary charge:    -0.000006    0.393416
0.000000
*My question are what does it mean when the min charge density is negative?
and what difference does it make between the negative min charge density and
positive min charge dendity. *

Also, when I do the density of state calculation for the cells above (SiC
with Cs at substitutional site of C and Si), I found an extra peak in the
band gap and :
    for Cs at C site in SiC, the extra peak is close to the conduction band
minimum
    for Cs at Si site in SiC, the extra peak is closed to the valence band
maxnimum

*So does it have something to do with the charge density, I found to be
starting with negative and postitive above?I mean is there a correlation
here or they are totally from different thing?
*
I'm sorry if my questions are confusing or do not make any sense, and I
really appreciate any input you have for me.

Best Regards,

Tram Bui

M.S. Materials Science & Engineering
trambui at u.boisestate.edu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20110928/18158c81/attachment.html>