DFT vs Van de Waals: Explaining the Difference

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In summary, Density Functional Theory (DFT) is a method used to calculate electronic properties of materials. However, it does not accurately describe Van der Waals interactions, which are non-local correlation effects. This is because the exchange-correlation potentials used in DFT are local and cannot capture this type of interaction. There have been efforts to improve DFT by including Van der Waals interactions, but it is still not able to fully capture non-local correlations.
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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..."
 
  • #3
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.
 
  • #4
Thank you very much!
 

FAQ: DFT vs Van de Waals: Explaining the Difference

1. What is the main difference between DFT and Van der Waals interactions?

DFT (Density Functional Theory) is a method used in computational chemistry to calculate the electronic structure of molecules, while Van der Waals interactions refer to weak forces between atoms or molecules that are not covalently bonded.

2. How does DFT take into account Van der Waals interactions?

DFT calculations can include the effects of Van der Waals interactions by using methods such as dispersion corrections or incorporating Van der Waals density functionals into the calculations.

3. Can DFT accurately predict Van der Waals interactions?

While DFT can provide a good estimation of Van der Waals interactions, it is not always accurate and can be improved by using more advanced methods such as post-Hartree-Fock calculations.

4. Are there any limitations to using DFT for studying Van der Waals interactions?

Yes, DFT calculations are limited by the size of the system being studied and the level of theory used. DFT is also not accurate for systems with significant dispersion or non-local electron correlation effects.

5. Which method is better for studying Van der Waals interactions - DFT or molecular mechanics?

It depends on the specific system and the level of accuracy needed. DFT is more computationally expensive but can provide more accurate results, while molecular mechanics is faster but less accurate. Both methods have their own advantages and limitations and can be used in combination for a more comprehensive study of Van der Waals interactions.

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