Modeling hydrogen bonds in three dimensions

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Molecular Modeling

Background:

• The Lippencott-Schroeder model is a standard for hydrogen bond interactions.
• Previous calculations often imposed constraints on proton movement.

Purpose of the Study:

• To recalculate the effective potential of hydrogen bonds using a more flexible proton model.
• To investigate the impact of proton mobility on the interaction potential.

Main Methods:

• Adiabatic treatment of proton configuration.
• Recomputation of proton position at varying interatomic distances.
• Utilizing the Lippencott-Schroeder bent bond model.

Main Results:

• The 'hard core' repulsion is an artifact of restricted proton movement.
• Allowing three-dimensional proton motion eliminates the hard core.
• Proton displacement from the atomic axis occurs at shorter separations.

Conclusions:

• Proton mobility significantly alters hydrogen bond potentials.
• The assumption of fixed proton angles is unrealistic and affects calculated potentials.
• Bond bending can modify bond anharmonicity, potentially reversing it.