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Phonon driven proton transfer in crystals with short strong hydrogen bonds
F Fontaine-Vive1, M R Johnson, G J Kearley
1Institut Laue Langevin, BP 156, 38042 Grenoble Cedex 9, France.
The Journal of Chemical Physics
|July 11, 2006
Summary
Proton migration in hydrogen bonds is driven by low-frequency vibrations. At intermediate temperatures, protons become bistable, transferring between donor and acceptor atoms in organic crystals.
Area of Science:
- Solid-state chemistry
- Materials science
- Computational physics
Background:
- Understanding proton migration in hydrogen bonds is crucial for various chemical and physical processes.
- Previous studies identified low-frequency vibrations as key to stabilizing crystal structures with shifted hydrogen bond potentials.
Purpose of the Study:
- To investigate proton migration mechanisms in short, strong hydrogen bonds within three organic crystalline systems.
- To extend the understanding of temperature-dependent proton dynamics in hydrogen-bonded materials.
Main Methods:
- Inelastic neutron scattering (INS) for structural and vibrational analysis.
- Density functional theory (DFT) based simulations for atomic-level insights.
- Molecular dynamics (MD) simulations to capture temperature-dependent proton behavior.
Main Results:
- The mechanism of low-frequency vibrations stabilizing hydrogen bonds is confirmed in new systems.
- Proton transfer from donor to acceptor atoms is observed in N-H...O hydrogen bonds.
- Protons exhibit bistable behavior, dynamically switching positions in an intermediate temperature range.
Conclusions:
- Low-frequency vibrations play a significant role in proton dynamics in short, strong hydrogen bonds.
- Proton bistability and transfer are key features influencing the behavior of these hydrogen bonds with temperature.
- Specific phonon modes can modulate the proton's potential energy surface in hydrogen bonds.
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