Influence of Coulomb-attenuation on exchange–correlation functional quality

Michael J. G. Peach, Aron J. Cohen, David J. Tozer, Phys. Chem. Chem. Phys., 8 4543–4549, 2006.


This paper is not as widely known as its citation count suggests. We were one of the first groups to consider the parameter-dependence of Coulomb-attenuated/ range-separated functionals. Here, in something of a follow-up to our original assessment of CAM-B3LYP, we highlighted the difficulty of satisfying known exact conditions that the exchange–correlation functional should satisfy (which are essential to the accurate description of certain types of excited states), and the problem of maintaining reasonable performance for ground-state properties. The CAM-B3LYP functional of Yanai, Tew and Handy is an example where the respective demands are well-balanced, resulting in good all-round accuracy.

Further information, including details of subsequent work in this area, can be found on the Functionals research page. For the abstract, and access to the full text, see below.


The dependence of functional quality on the attenuation parameters—which control the limiting (r12 → 0, ∞) values and the rate of attenuation—is investigated for a Coulomb-attenuated exchange–correlation functional. For the attenuation and functional form considered, satisfaction of an exact long-range condition is detrimental for properties such as atomisation energies and bond lengths, but does improve classical reaction barriers and small molecule electronic excitation energies. The functionals considered can provide high quality valence, Rydberg, intramolecular and asymptotic intermolecular charge transfer (CT) excitations, but none are able to provide a simultaneously optimal description of all classes; CT excitations are not necessarily improved compared to those from conventional functionals. The study highlights the need for further development of Coulomb-attenuated functionals.

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