The ABINIT Users Mailing List ( CLOSED )

[Masayoshi Mikami <mmikami@yk.rim.or.jp>]

Hello,

I have little time, but wanted to point out several things:
1) Please read textbooks, about O2 molecule; 
   O2 should be treated as 
   nspol 2
   spinat 0.0 0.0 1.0 
          0.0 0.0 1.0
   see Test_v1/t09.in for example to see how to set "occ"/"occopt"
   (test cases including "oxygen" can be found by typing
    grep -i oxygen Test*/*.in
   Then, the Test_v1/t09 is noticed as such a example...)
   (It will be a good idea to try Test_* in this occasion.)

2) Which type of O pseudopotential(PP) is adopted ?
   Sufficient ecut may depends on the type of the PP...

3) How about adopting the special k-point (0.25, 0.25, 0.25) 
   for simple cubic supercel ?

4) Kindly read the netiquette 
     http://www.abinit.org/community/?text=netiquette
   and try to avoid HTML e-mails; in Plain Text, please...

Good luck,
Masayoshi

On Sat, 4 Dec 2004 10:37:53 +0800 (CST)
"Zhenhua Zeng" <myid520@163.com> wrote:

> Dear abinit users, 
>     Now, I want to predict using oxygen. So I test some well-known 
> situations, such as bond length and bond energy (atomisation energy) of 
> oxygen. The error of bond length is less than 1%. But the error of bond 
> energy is very large. The calculated result using every pseudo potential 
> downloaded from the web cite is between 8.5ev and 9.7ev. But The 
> experimental data is 5.12ev. The result calculated using VASP and CASTEP 
> are between 5.5ev and 6.5ev. The input file is given at below which based 
> on Tutorial\t21.in. In the input file, the acell and ecut have been tested 
> for the convergence of calculation. I want to know why it differs so much 
> from experimental data and other calculations Does there have something 
> wrong in my input file, the method used in tutorial to calculate bond 
> energy (atomisation energy) can’t be used here, Or there has something 
> wrong else? In addition, Can I use oxygen for prediction only depends on 
> the good tested result of bond length? Your help !
 will be greatly appreciated!
> Best regards.
> Zhenhua Zeng
> Hunan University, PR. china
> 
> ####  input files   ##############
> #calculate oxygen molecular and atom
> #common parameters
> ndtset 2
> ixc 1 or ixc 3 or ixc 7 or ixc 11 for different pseudo potential
> acell 3*12  Bohr 
> ecut  30.0  Hatree
> nstep 100
> ngkpt 2 2 2
> kptopt 1
> ntypat 1
> znucl  8
> diemac 1.0   
> diemix 0.5   
> 
> #the parameters for oxygen atoms
> nsppol1 2             ##SPin POLarization calculation of oxygen atom
> spinat1 0.0 0.0 1.0
> natom1 1           
> typat1 1
> xcart1 3*0.0        
> toldfe1 1.0d-6
> 
> #The parameters for oxygen molecular
> natom2 2   
> typat2 1 1        
> xcart2   -1.145 0.0 0.0    #the bond length of oxygen molecular is 
>           1.145 0.0 0.0    #about 2.29 Bohr
> ionmov2  3  
> ntime2  100  
> tolmxf2  5.0d-5 
> toldff2  5.0d-6


-- 
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Masayoshi Mikami (Yokohama, Japan)
  home:    mmikami@yk.rim.or.jp
  webmail: mmikami_yk@yahoo.co.jp
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