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User:Szggr/sandbox/Tkatchenko-Scheffler method

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The Tkatchenko-Scheffler (TS) method is a computational chemistry method to model van der Waals parameters based on free atomic data. The model gives a good approximation for the pairwise interaction term.

Formulation

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A good approximation for van der Waals interactions is a pairwise approximation in the form:

(1)

The sum is over all atoms in the system , the function is a damping function that, in general, can depend on the free atom van der Waals radii and the distance between atoms and . The damping function used in the original method is:

(2)

with using the sum of atomic radii and having and as free parameters to fit.

According to the formula of Equation (1), a full description of the van der Waals forces in this approximation consists of determining the coefficients for the set of atomic radii used. The Tkatchenko-Scheffler method expressed the heteronuclear parameter as a function of homonuclear parameters with the following combination rule:

(3)

The original work is based on free atom reference data of Chu and Dalgarno.

References

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