Page 1 of 1

Number of electrons as a function of RWIGS radius

Posted: Fri May 28, 2010 8:14 am
by ledssiul
I have calculated, for Co_1 (d8 s1), the s, d, and total number of electrons as a function of Wigner-Seitz (RWIGS) radio using a simple INCAR, a big cubic box (3*18), GGA, and just Gamma point.

...
ISPIN = 2
VOSKOWN = 1
ISMEAR = 0 (Gaussian)
SIGMA = 0.01

NPAR = 1
LORBIT = (I tried four values : 0,1,2,5)
RWIGS = (I tried the interval: 0.1, ... ,3.0 [angstroms])
...

Here some unexpected results for different RWIGS radius:

"total charge"
[e_s == s-electrons]
[e_d == d-electrons]
[e_t == total number of electrons]

1.- RWIGS = 0.1 [angstroms]

a) e_s = -0.09 (e_s is NEGATIVE)
b) e_d = 5.38
c) e_t = 5.29 (e_t < e_d !!!)

2.- RWIGS = 0.7 [angstroms]

a) e_s = 0.00 (the curve for e_s crosses the zero level)
b) e_d = 5.75
c) e_t = 5.75 (there is a crossing in the curves for e_d and e_t)

3.- RWIGS = 2.3 [angstroms]

a) e_s = 1.04
b) e_d = 7.57 (here, there is a MAXIMUM in the curve for the e_d)
c) e_t = 8.61

4.- RWIGS = 2.5 [angstroms]

a) e_s = 1.09
b) e_d = 7.54 (this value is LOWER than in RWIGS=2.3)
c) e_t = 8.64 (here, there is a MAXIMUM in the curve for the e_t)

5.- RWIGS = 3.0 [angstroms]

a) e_s = 1.18
b) e_d = 7.34 (this value is even lower than before)
c) e_t = 8.52 (now I have LESS total number of electrons)


I was expecting to have the number of d-electrons --> 0 for RWIGS --> 0, and also, I was not to expecting to have the MAXIMUM values in the e_d and e_t curves since I am dealing just with one atom.

I tried Co_2, Co_43 and Co_bulk with similar results.

The question is, am I misunderstanding the real meaning of RWIGS? Is there a reason to get such kind of estrange behavior? or do I have to setup an extra flag?

Thanks in advance for any clarification.

Luis

PS. There exist a similar post, not too many days ago about the same topic, but until now there is no answer, that is the reason why I decided to post my own thread.
<span class='smallblacktext'>[ Edited ]</span>

Number of electrons as a function of RWIGS radius

Posted: Thu Jul 01, 2010 8:22 am
by admin
this issue has been discussed in the forum, please search for the corresponding postings