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Updated: May 6, 2026

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Published on: July 19, 2019
Kinetic isotope effect in malonaldehyde determined from path integral Monte Carlo simulations
Jing Huang1, Marcin Buchowiecki, Tibor Nagy
1Department of Chemistry, University of Basel, Klingelbergstrasse 80, Basel, Switzerland. m.meuwly@unibas.ch.
The kinetic isotope effect in malonaldehyde was calculated using quantum simulations. Zero-point energy effects significantly influence this effect, with tunneling playing a minor role at room temperature.
Area of Science:
- Chemical Dynamics
- Quantum Chemistry
- Spectroscopy
Background:
- Intramolecular proton transfer is a fundamental process in chemistry.
- Understanding the kinetic isotope effect (KIE) provides insights into reaction mechanisms.
Purpose of the Study:
- To determine the primary H/D kinetic isotope effect in malonaldehyde.
- To investigate the temperature dependence of the KIE.
- To elucidate the contributions of zero-point energy and tunneling to the KIE.
Main Methods:
- Quantum instanton path integral Monte Carlo simulations.
- Direct evaluation of the kinetic isotope effect using thermodynamic integration.
- Utilized a fully dimensional and validated potential energy surface.
Main Results:
- Calculated KIE for malonaldehyde between 250 and 1500 K.
- Obtained a KIE of 5.2 ± 0.4 at room temperature.
- Observed significant temperature dependence of the KIE, particularly at low temperatures.
Conclusions:
- Zero-point energy effects are the dominant factor in the malonaldehyde KIE.
- Quantum tunneling plays a minimal role in the KIE at room temperature.
- Simulation methods provide accurate KIE predictions for proton transfer reactions.
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