[Wien] Slab covergence

[Da Silva, Juarez]

Dear Pengfei

 

I did recent surface energy calculations employing the WIEN2k and
different codes and these results are published in 

 

Surface Science 600, 703 (2006);

Phys. Rev. B 73, 125402 (2006);

Phys. Rev. B 71, 195416 (2005)

 

There are several tests concerning the convergence of the surface energy
as a function of the number of layers 

In the slab and the reasons behind the increasing of the surface energy
with slab thickness.

 

Bye

Juarez

 

 

 

-----Original Message-----
From: wien-bounces at zeus.theochem.tuwien.ac.at
[mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of MoonfalL
Sent: Friday, August 11, 2006 9:41 AM
To: wien
Subject: [Wien] Slab covergence

 

Dear Prof. and Wien user:

 

I want to test the surface energy's covergence; according to the
suggestions                 
at this list,I do the following calculations:

 

slab with : 7 \ 9 \ 11 atom layers

           each  model  in  15 \ 20 \ 25 bohr vacuum thickness

 

the result list here:

 

E_slab

vacuum    7(layers)       9(layers)      11(layers)

15 -48168.15027 -61930.51462 -75692.87704

20 -48168.14974 -61930.51284 -75692.87596

25 -48168.14885 -61930.51269 -75692.87490                               
 

 

 

surface energy (E_slab - n* E_bulk)

            7          9            11

15        0.21361    0.23894      0.26620

20        0.21414    0.24072     0.26728

25        0.21503    0.24087     0.26834

 

RKM = 6

k-points

           8(7*7*1)

my questions are:

  1) why the energy increases when the vacuum thickness increases?

  2) then  why the surface energy insreases when the atom layers
increases?                  
  3) then how to judge the  vacuum thickness is enough,

     and the atom layers is enough?

 

Can somebody give me some advices? Thanks very much!

 

also I check the :VZERO, but it is too different from bulk system,
tomorrow I will give the  
:VZERO numerical value

 

the attachments are  struct files !

 

Best!

 
Pengfei                                                       


-- 
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Guan Pengfei,  Ph. D
Inst.f. Physics, Tsinghua U, Beijing, China
Phone: +86-010-6218-2756        Mobile: +86-138-1060-9671
Email: miracle.fei at gmail.com 
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