|Posted on November 11, 2017 at 10:05 AM|
The so-called van der Waals (vdW) interactions are one of the weakest forces in nature and yet they govern the stability of molecules and materials, having an essential role in molecular recognition, the stability of the double-helical structure of DNA and molecular adsorption processes on surfaces, amongst others. So far, only a universal relationship between the van der Waals energy and the distance between two atoms or molecules was known, being widely used to model these interactions in physics, chemistry, and biology.
In a recent work published in Phys. Rev. A., another universal signature of van der Waals interactions has been unveiled. This new fingerprint of weak molecular interactions is numerically more robust than the earlier condition on the energy and could thus provide a handy tool for the development of new methods to analyze the electronic structure of molecular systems. By means of perturbation theory, we have shown that the interelectronic part of the pair density, which is the workhorse of electronic structure methods and provides a distribution of the electron pairs in the space, decays as 1/R^3 for two molecular fragments separated by a distance R. The main author of this work is Mireia Via-Nadal (PhD student at the UPV/EHU and the DIPC), to which Mauricio Rodriguez-Mayorga has also contributed.
This result opens the door to produce density-dependent non-covalent interaction corrections in density and density matrix functional theories (DFT and DMFT). This possibility will be explored in our laboratory.
This work has been published in Phys. Rev. A.