| Re: Binding energy calculation ( No.1 )|
- Date: 2006/10/12 23:05
- Name: T.Ozaki
Could you check the standard output ?
If you see "The system is molecule." in the standard output,
it is Okay. But I wonder that the part "molecule" can be
"chain", "slab", or "bulk", since the cutoff radius of basis function
for W is long. Then, the "molecular calculation" you intend becomes
the band calculation. The cell size should be determined by the largest
distance between atoms you try, and should be fixed during the calculation of
energy curve. Otherwise, you will have some artifact effect arising from
the unit cell size.
Also, the pseudopotential of W is a deep one. Thus, the dependency on
"scf.energycutoff" should be checked carefully.
As for O2 case, with above things the basis set convergence should be
checked. Elements in the sixth and seventh columns tend to requires
a large number of basis function for the convergence.
You can find the convergence properties of the O2 bond length with
respect to basis functions in
Phys. Rev. B 69, 195113 (2004).