Abstract
The role that van der Waals (vdW) attractive forces play in the hydration and association of atomic hydrophobic solutes such as argon (Ar) in water is reanalyzed using the local molecular field (LMF) theory of those interactions. In this problem, solute vdW attractive forces can reduce or mask hydrophobic interactions as measured by contact peak heights of the ArAr correlation function compared to reference results for purely repulsive core solutes. Nevertheless, both systems exhibit a characteristic hydrophobic inverse temperature behavior in which hydrophobic association becomes stronger with increasing temperature through a moderate temperature range. The new theoretical approximation obtained here is remarkably simple and faithful to the statistical mechanical LMF assessment of the necessary force balance. Our results extend and significantly revise approximations made in a recent application of the LMF approach to this problem and, unexpectedly, support a theory of nearly 40 years ago.
| Original language | English |
|---|---|
| Pages (from-to) | 6272-6276 |
| Number of pages | 5 |
| Journal | Journal of Physical Chemistry B |
| Volume | 122 |
| Issue number | 23 |
| DOIs | |
| State | Published - Jun 14 2018 |
| Externally published | Yes |
Funding
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This work was supported by Sandia’s LDRD program (M.I.C. and S.B.R.) and by the National Science Foundation, grant CHE-1300993 (A.G. and J.D.W.). This work was performed, in part, at the Center for Integrated Nanotechnologies (CINT), an Office of Science User Facility operated for the U.S. DOE’s Office of Science by Los Alamos National Laboratory (contract DE-AC52-06NA25296) and SNL.