Publication

Path integral evaluation of the equilibrium isotope effect in [1,5] sigmatropic hydrogen shift reactions

2009
Journal Articles

Abstract

The path integral methodology for computation of the equilibrium isotope effect is described and applied to three [1,5] sigmatropic hydrogen shift reactions. An efficient estimator for the derivative of the free energy is used, which shortens the computation time by the factor of about 60. Calculations reveal that the correction beyond the usual harmonic approximation for nuclear motion amount up to 30 % of the symmetry reduced reaction free energy. The numerical results are compared with recent experiments of Doering and coworkers, confirming the accuracy of the most recent measurement as well as concerns about compromised accuracy, due to side reactions, of another measurement.

Official source

https://infoscience.epfl.ch/entities/publication/1adb77f4-c44c-4b14-a140-3fd9cb7ba518

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2009
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/1adb77f4-c44c-4b14-a140-3fd9cb7ba518

About this result

Related concepts (32)

Chemical reaction

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

Gibbs free energy

In thermodynamics, the Gibbs free energy (or Gibbs energy as the recommended name; symbol ) is a thermodynamic potential that can be used to calculate the maximum amount of work, other than pressure-volume work, that may be performed by a thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy is expressed as where p is pressure, T is the temperature, U is the internal energy, V is volume, H is the enthalpy, and S is the entropy.

Thermodynamic free energy

In thermodynamics, the thermodynamic free energy is one of the state functions of a thermodynamic system (the others being internal energy, enthalpy, entropy, etc.). The change in the free energy is the maximum amount of work that the system can perform in a process at constant temperature, and its sign indicates whether the process is thermodynamically favorable or forbidden. Since free energy usually contains potential energy, it is not absolute but depends on the choice of a zero point.

Related publications (5)

Path integral evaluation of the equilibrium isotope effect in [1,5] sigmatropic hydrogen shift reactions

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