DFT vs Van de Waals: Explaining the Difference

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Discussion Overview

The discussion centers on the limitations of Density Functional Theory (DFT) in describing Van der Waals interactions, exploring theoretical aspects and implications for simulations in surface physics.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant inquires about the general reasons why DFT does not adequately describe Van der Waals interactions.
  • Another participant references a method that incorporates Van der Waals interactions into DFT using Maximally-Localized Wannier functions, suggesting potential improvements for simulating surface-physics processes.
  • A different participant argues that Van der Waals forces are non-local correlation effects, while the exchange-correlation potentials in DFT are local, indicating a fundamental limitation in capturing these interactions.

Areas of Agreement / Disagreement

Participants express differing views on the capabilities of DFT regarding Van der Waals interactions, with some suggesting improvements while others highlight inherent limitations. No consensus is reached on the effectiveness of DFT in this context.

Contextual Notes

The discussion does not resolve the specific mathematical or theoretical assumptions underlying the claims about DFT and Van der Waals interactions.

thuong
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Hi everybody,

Can you tell me, in general, why Density Functional Theory does not describe the Van de Waals interaction?

Many thanks,
 
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Perhaps this can help. An excerpt from http://arxiv.org/abs/0809.1491

"The method recently developed to include Van der Waals interactions in the Density Functional Theory by using the Maximally-Localized Wannier functions, is improved and extended to the case of atoms and fragments weakly bonded (physisorbed) to metal and semimetal surfaces, thus opening the way to realistic simulations of surface-physics processes, where Van der Waals interactions play a key role..."
 
My understanding is that the Van der Waals force is something that is a non-local correlation effect. The exchange-correlation potentials used in DFT are local, so they can't capture this effect. Well, GGA is semi-local but it is not good enough to model a real non-local correlations.
 
Thank you very much!
 

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