[Wien] spin distribution in organic

[Andrei Postnikov]

Hallo Hai,

Without yet calculating organic magnets with WIEN, but based on
general experience, here are some comments:

On Thu, 11 Mar 2004, Yue Hai wrote:

| Dear sir:
|     I have a larger organic system (36 inequivalent atoms per unit cell )
| and want to study the magntic character of it. The experiment has shown
| that there is about 1.0 μB/mol for the  magnet moment. From the spin
| polarization calculation , I found that the  magnet moment of one molecule
| is  1.00μB, which is in agreement with the experiment.

This is good.

| But there is a
| larger spin population in the interstitial region. For example: the sum of
| spin populations on all atoms is about 0.58μB/mol, while the spin
| population in the interstitial region is about 0.42μB/mol.   I don not
| know if this is correct or possible.

This is normal.

|    I want to know the reason of it :
|      1: if this is because of the samll MT sphere  or other inappropriate
| parameters used in the  calulation?.

Small MT does not mean "inappropriate". Local magnetic moments
are loosely defined anyway. (Calculate them with a TB method and you'll
get very different numbers).

|      2: or it is due to the fact that there is no localized spin center in
| the organic material  because of the hyperconjugation effect,while the
| calculated spin populatoin on the atom is confined in the MT sphere,  so
| the spin population in the interstitial region  is larger?

Your C is probably almost not magnetic, but O and N and bonds between
them carry some moment. You can try Bader analysis but I doubt this will
make much sense. Plot your magnetic density and look at it, to begin with.

Good luck,

Andrei

 +-- Dr. habil. Andrei Postnikov ----- Tel. +49-541-969.2377 -- Fax .2351 ---+
 | Universitaet Osnabrueck - Fachbereich Physik, D-49069 Osnabrueck, Germany |
 +-- apostnik at uos.de --------- http://www.home.uni-osnabrueck.de/apostnik/ --+

|      3: I want to know the spin distribution in the molecule space. If 2 is
| correct, is it  appropriate to  plot the spin electron density  (the spin
| up electrons minus spin down  electron) to represent the spin distribution
| in the molecule?
|
|  The parameters I used in the calculation :
|    The RMT for H is 0.6,  and the RMTs for O, C, N are  1.1-1.2
|    RKmax=2.5 , Gmax=20 and 10 k-points in the IBZ
|
|    It wil be very grateful If some can help me or give me  advice about it
| .
|
|
| Best wishes
|
| Hai
|