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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Fixed-node diffusion Monte Carlo study of the structures of m-benzyne
1Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853, USA. al-saidi@cornell.edu
The Journal of Chemical Physics
|April 25, 2008
Summary
Diffusion Monte Carlo (DMC) calculations reveal the monocyclic form of m-benzyne is more stable than the bicyclic form. This finding aligns with advanced coupled cluster theory, confirming theoretical predictions for this important molecule.
Area of Science:
- Quantum Chemistry
- Computational Chemistry
- Molecular Modeling
Background:
- Understanding the stable structures of reactive intermediates like m-benzyne is crucial in organic chemistry.
- Previous studies utilized coupled cluster theory to determine equilibrium structures.
Purpose of the Study:
- To accurately determine the relative energies of the monocyclic and bicyclic forms of m-benzyne using Diffusion Monte Carlo (DMC).
- To compare DMC results with high-level coupled cluster (CC) calculations.
Main Methods:
- Diffusion Monte Carlo (DMC) calculations were performed.
- Multiconfiguration self-consistent field (MCSCF) trial wave functions were employed.
- A complete active space configuration interaction (CASCI) with eight electrons in eight orbitals [CAS(8,8)] was used, with reoptimized coefficients in the presence of a Jastrow factor.
Main Results:
- The monocyclic structure of m-benzyne was found to be lower in energy than the bicyclic structure.
- The energy difference was calculated to be 1.9(2) kcal/mole.
- DMC results showed excellent agreement with coupled cluster theory benchmarks.
Conclusions:
- Diffusion Monte Carlo accurately predicts the energetic preference for the monocyclic structure of m-benzyne.
- The study validates DMC as a reliable method for investigating the energetics of molecular systems.
- Theoretical agreement between DMC and coupled cluster methods strengthens the understanding of m-benzyne's stability.
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