DFT-D3: Difference between revisions
No edit summary |
|||
(52 intermediate revisions by 4 users not shown) | |||
Line 1: | Line 1: | ||
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 default values for damping function parameters are available for | *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/.}} | ||
on the webpage | |||
The 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 | |||
== Related | == 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/> | |||
---- | ---- | ||
[[ | [[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