Chapter title |
Short-Range Cut-Off of the Summed-Up van der Waals Series: Rare-Gas Dimers.
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Chapter number | 625 |
Book title |
Density Functionals
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Published in |
Topics in current chemistry, April 2015
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DOI | 10.1007/128_2015_625 |
Pubmed ID | |
Book ISBNs |
978-3-31-919691-6, 978-3-31-919692-3
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Authors |
Abhirup Patra, Bing Xiao, John P. Perdew |
Editors |
Erin R. Johnson |
Abstract |
van der Waals interactions are important in typical van der Waals-bound systems such as noble gas, hydrocarbon, and alkaline earth dimers. The summed-up van der Waals series of Perdew et al. 2012 works well and is asymptotically correct at large separation between two atoms. However, as with the Hamaker 1937 expression, it has a strong singularity at short non-zero separation, where the two atoms touch. In this work we remove that singularity (and most of the short-range contribution) by evaluating the summed-up series at an effective distance between the atom centers. Only one fitting parameter is introduced for this short-range cut-off. The parameter in our model is optimized for each system, and a system-averaged value is used to make the final binding energy curves. This method is applied to different noble gas dimers such as Ar-Ar, Kr-Kr, Ar-Kr, Ar-Xe, Kr-Xe, Xe-Xe, Ne-Ne, He-He, and also to the Be2 dimer. When this correction is added to the binding energy curve from the semilocal density functional meta-GGA-MS2, we get a vdW-corrected binding energy curve. These curves are compared with the results of other vdW-corrected methods such as PBE-D2 and vdW-DF2, and found to be typically better. Binding energy curves are in reasonable agreement with those from experiment. |
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