A New Hydrogen Bond Angle/Distance Potential Energy Surface of the Quantum Water Dimer
Scott, JN1; Vanderkooi, JM2,*
1 Department of B Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, 257 Anatomy-Chemistry Bldg., 3620 Hamilton Walk, Philadelphia, PA 19104, USA
* Correspondence: Tel.: (215)898-8783, Fax: (215)573-2085; Email: vanderko@mail.med.upenn.edu
Key Words: water dimer, potential energy surface, hydrogen bonds, water structure, quantum dimer, hydrogen bond angle
Received September 2, 2009; accepted January 8, 2010. Published February 5, 2010; available online February 5, 2010
Summary
The relative effects of H-bond angle and O-O distance were examined using a series of quantum mechanical calculations on a water dimer. The geometries were constructed in such a way that H-bond angle and O-O separation were the only two independent variables, and this allowed for calculations of energies and atomic charges as a function of H-bond angle and O-O distance. Our findings show that O-O separation within the range 0.25 nm to 0.40 nm has a lesser effect on system energy and charge as compared to changes in H-bond angle, and that energy as a function of O-O separation behaves very much like a Morse potential for linear H-bonds but not for bent hydrogen bonds. Recent literature in the water dimer field is discussed, as is the application of the current findings to bulk water.