[Wien] Anyone done Silicium yet?

[koitzsch]

I think, it is actually quite common, that LDA underestimates gap sizes. I
remember from a Wien workshop that Prof. Blaha said something to the effect,
that LDA calculates ground state properties (e.g. total energy, densities
etc.), which should not be mixed up with e.g. excitation gaps.

If you want to obtain better "gaps" you have to use other methods, like GW
for instance.

Best Regards

Christian

PS.: I think your Si LDA gap is the "correct" LDA gap, so nothing to worry
about...

Christian Koitzsch
University Neuchatel
Dep. of Physics
CH-2000 Neuchatel
Switzerland



----- Original Message ----- 
From: "Michael Frotscher" <frotscher at chemie.uni-hamburg.de>
To: <wien at zeus.theochem.tuwien.ac.at>
Sent: Friday, January 09, 2004 6:34 PM
Subject: [Wien] Anyone done Silicium yet?


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> Hello, Wien-ML
>
> Having resolved the choice-of-origin-issue (thanks to all), I did some
> calculations on substances in the diamond lattice. Everything went fine,
> although I'm not quite sure about the results.
>
> I calculated DOS of Diamond and Silicium and both look like one would
expect.
> But I found band gaps that are smaller than quoted in the literature. Si
had
> a gap of 0.041Ry which equals 0.557eV (literature: 1.09eV). The difference
in
> diamond is less, but there: 4.14eV opposed to the 5.2eV found in the
> literature.
>
> How can this be explained?
> - -- 
> Michael Frotscher
> Institute of Inorganic and Applied Chemistry
> University of Hamburg, Germany
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