[Wien] total energy of N2, O2, and F2

[Gilles Hug]

Hi xn22,
Did you have any follow up on that topic?

I found 1.10236 Angst. for the equilibrium distance and -219.054734 Ryd 
for the energy of the N2 molecule.

I have used a tetragonal unit cell (#123 P4/m m m)  with one 
in-equivalent atom in (0, 0, z). The molecule is build by the mirror. 
Then I can vary the bond length (with z). The size of the unit cell was 
10.3463 bohr. It might be useful to increase a bit the UC but I have 
not tried.
I don't know of using fcc and what would be the benefit.

However, RKM *does* make a difference.
In a first run I had :
:RKM  : MATRIX SIZE 4955LOs:  10  RKM= 6.37  WEIGHT= 1.00  PGR:
:ENE  : *WARNING** TOTAL ENERGY IN Ry =         -219.047104

Then you need to recompile Wien2k, the second run gave :
:RKM  : MATRIX SIZE 6413LOs:  10  RKM= 6.98  WEIGHT= 1.00  PGR:
:ENE  : ********** TOTAL ENERGY IN Ry =         -219.050815

So with 3.66 as in your case is certainly *not* enough.

I think, it does not make too much sense to use the experimental 
equilibrium distance. DFT-GGA give a slightly to big equilibrium 
volume, but it is ok. If you want to compare to other structures all 
have to be in fundamental state. I think it is more consistent that 
way.

Best,
Gilles


Le 24 nov. 03, à 23:00, xn22 at drexel.edu a écrit :

> Hi, WIEN users:
>
> I did calculations for total energy of N2, O2, and F2. They are:
>
> N2: -218.61075
> O2: -300.048083 (with spin polarization)
> F2: -399.143937
>
> I realized at least total energy of N2 is different with one user who 
> posted on this list.
>
> I am really appreciated you if you can share your results with me. I 
> think I used
> almost experimental bond-length with GGA (pw91). Two things I am worry 
> are following:
>
> 1. I didn't put the atoms on fcc site as Peter suggested on this list. 
> Is this make difference?
>
> 2. WIEN2k_03 trucated RKM to small number such as N2(3.66), O2(3.83), 
> F2(4.71) even I asked standrad 7 in case.in1 file. Is this also 
> influence the output of total energy?
>
> Thanks in advance for any feedback.
>
> Happy Thanksgiving.
>
> Xiliang
>
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>
Dr. Gilles Hug
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