DFT-D3: Difference between revisions
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In the | In the DFT-D3 method of Grimme et al.{{cite|grimme:jcp:10}}, the following expression for the vdW dispersion energy-correction term is used: | ||
<math> E_{\mathrm{disp}} = -\frac{1}{2} \sum_{i=1}^{N_{at}} \sum_{j=1}^{N_{at}} \sum_{\mathbf{L}}{}^\prime \left ( f_{d,6}(r_{ij,L})\,\frac{C_{6ij}}{r_{ij,{L}}^6} +f_{d,8}(r_{ij,L})\,\frac{C_{8ij}}{r_{ij,L}^8} \right ).</math> | :<math> E_{\mathrm{disp}} = -\frac{1}{2} \sum_{i=1}^{N_{at}} \sum_{j=1}^{N_{at}} \sum_{\mathbf{L}}{}^\prime \left ( f_{d,6}(r_{ij,L})\,\frac{C_{6ij}}{r_{ij,{L}}^6} +f_{d,8}(r_{ij,L})\,\frac{C_{8ij}}{r_{ij,L}^8} \right ).</math> | ||
Unlike in the method {{TAG|DFT-D2}}, the dispersion coefficients <math>C_{6ij}</math> are geometry-dependent as they are | Unlike in the method {{TAG|DFT-D2}}, the dispersion coefficients <math>C_{6ij}</math> are geometry-dependent as they are calculated on the basis of the local geometry (coordination number) around atoms <math>i</math> and <math>j</math>. Two variants of DFT-D3, that differ in the damping functions <math>f_{d,n}</math>, are available. | ||
=== DFT-D3(zero) === | |||
In the zero-damping variant of DFT-D3,{{cite|grimme:jcp:10}} invoked by setting {{TAG|IVDW}}=11, the damping function reads | |||
:<math>f_{d,n}(r_{ij}) = \frac{s_n}{1+6(r_{ij}/(s_{R,n}R_{0ij}))^{-\alpha_{n}}}</math> | |||
where <math>R_{0ij} = \sqrt{\frac{C_{8ij}}{C_{6ij}}}</math>, the parameters <math>\alpha_6</math>, <math>\alpha_8</math>, <math>s_{R,8}</math> and <math>s_{6}</math> are fixed at values of 14, 16, 1, and 1, respectively, while <math>s_{8}</math> and <math>s_{R,6}</math> are adjustable parameters whose values depend on the choice of the exchange-correlation functional. | |||
Optionally, the following parameters can be defined in the {{FILE|INCAR}} file (the given values are the default ones): | |||
<math> | *{{TAG|VDW_RADIUS}}=50.2 : cutoff radius (in <math>\AA</math>) for pair interactions considered in the equation of <math> E_{\mathrm{disp}}</math> | ||
*{{TAG|VDW_CNRADIUS}}=20.0 : cutoff radius (in <math>\AA</math>) for the calculation of the coordination numbers | |||
*{{TAG|VDW_S8}}=[real] : damping function parameter <math>s_8</math> | |||
*{{TAG|VDW_SR}}=[real] : damping function parameter <math>s_{R,6}</math> | |||
with <math> | === DFT-D3(BJ) === | ||
In the Becke-Johnson (BJ) damping variant of DFT-D3,{{cite|grimme:jcc:11}}, invoked by setting {{TAG|IVDW}}=12, the damping function is given by | |||
:<math>f_{d,n}(r_{ij}) = \frac{s_n\,r_{ij}^n}{r_{ij}^n + (a_1\,R_{0ij}+a_2)^n} </math> | |||
with <math>s_6=1</math> and <math>a_1</math>, <math>a_2</math>, and <math>s_8</math> being adjustable parameters. As before, the parameters {{TAG|VDW_RADIUS}} and {{TAG|VDW_CNRADIUS}} can be used to change the default values for the cutoff radii. | |||
Optionally, the parameters of the damping function can be controlled using the following {{FILE|INCAR}} tags: | |||
*{{TAG|VDW_S8}}=[real] | *{{TAG|VDW_S8}}=[real] | ||
*{{TAG|VDW_A1}}=[real] | *{{TAG|VDW_A1}}=[real] | ||
*{{TAG|VDW_A2}}=[real] | *{{TAG|VDW_A2}}=[real] | ||
{{NB|mind| | |||
*The default values for the damping function parameters are available for several {{TAG|GGA}} (PBE, RPBE, revPBE and PBEsol), {{TAG|METAGGA}} (TPSS, M06L and SCAN) and [[list_of_hybrid_functionals|hybrid]] (B3LYP and PBEh/PBE0) functionals, as well as [[list_of_hybrid_functionals|Hartree-Fock]]. If another functional is used, the user has to define these parameters via the corresponding tags in the {{TAG|INCAR}} file. The up-to-date list of parametrized DFT functionals with recommended values of damping function parameters can be found on the webpage https://www.chemie.uni-bonn.de/grimme/de/software/dft-d3/ and follow the link "List of parametrized functionals". | |||
*The DFT-D3 method has been implemented in VASP by Jonas Moellmann based on the dftd3 program written by Stefan Grimme, Stephan Ehrlich and Helge Krieg. If you make use of the DFT-D3 method, please cite reference {{cite|grimme:jcp:10}}. When using DFT-D3(BJ) references {{cite|grimme:jcp:10}} and {{cite|grimme:jcc:11}} should also be cited. Also carefully check the more extensive list of references found on https://www.chemie.uni-bonn.de/grimme/de/software/dft-d3/.}} | |||
== Related tags and articles == | |||
{{TAG|VDW_RADIUS}}, | |||
{{TAG|VDW_CNRADIUS}}, | |||
{{TAG|VDW_S8}}, | |||
{{TAG|VDW_SR}}, | |||
{{TAG|VDW_A1}}, | |||
{{TAG|VDW_A2}}, | |||
{{TAG|IVDW}}, | {{TAG|IVDW}}, | ||
{{TAG|DFT-D2}}, | {{TAG|DFT-D2}}, | ||
{{TAG| | {{TAG|DFT-ulg}}, | ||
[[DFT-D4]] | |||
== References == | == References == | ||
<references | <references/> | ||
---- | ---- | ||
[[ | [[Category:Exchange-correlation functionals]][[Category:van der Waals functionals]][[Category:Theory]] | ||
[[Category: |
Latest revision as of 15:04, 24 February 2025
In the DFT-D3 method of Grimme et al.[1], the following expression for the vdW dispersion energy-correction term is used:
Unlike in the method DFT-D2, the dispersion coefficients are geometry-dependent as they are calculated on the basis of the local geometry (coordination number) around atoms and . Two variants of DFT-D3, that differ in the damping functions , are available.
DFT-D3(zero)
In the zero-damping variant of DFT-D3,[1] invoked by setting IVDW=11, the damping function reads
where , the parameters , , and are fixed at values of 14, 16, 1, and 1, respectively, while and are adjustable parameters whose values depend on the choice of the exchange-correlation functional.
Optionally, the following parameters can be defined in the INCAR file (the given values are the default ones):
- VDW_RADIUS=50.2 : cutoff radius (in ) for pair interactions considered in the equation of
- VDW_CNRADIUS=20.0 : cutoff radius (in ) for the calculation of the coordination numbers
- VDW_S8=[real] : damping function parameter
- VDW_SR=[real] : damping function parameter
DFT-D3(BJ)
In the Becke-Johnson (BJ) damping variant of DFT-D3,[2], invoked by setting IVDW=12, the damping function is given by
with and , , and being adjustable parameters. As before, the parameters VDW_RADIUS and VDW_CNRADIUS can be used to change the default values for the cutoff radii.
Optionally, the parameters of the damping function can be controlled using the following INCAR tags:
Mind:
|
Related tags and articles
VDW_RADIUS, VDW_CNRADIUS, VDW_S8, VDW_SR, VDW_A1, VDW_A2, IVDW, DFT-D2, DFT-ulg, DFT-D4