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Updated: Jan 9, 2026
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Split Point Analysis and Uncertainty Quantification of Thermal-Optical Organic/Elemental Carbon Measurements
Published on: September 7, 2019
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Stochastic-SplitGAS: A Quantum Monte Carlo Multi-Reference Perturbation Theory Based on the Imaginary-Time Evolution
Luca Bonfirraro1, Oskar Weser1,2, Maru Song1
1Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
Journal of Chemical Theory and Computation
|December 3, 2025
Summary
A new quantum chemistry method, Stochastic-SplitGAS, accurately models complex electronic structures. It efficiently calculates dynamic correlation effects for improved descriptions of magnetic and optical properties.
Area of Science:
- Quantum Chemistry
- Computational Chemistry
- Electronic Structure Theory
Background:
- Modeling systems with many unpaired electrons is challenging.
- Accurate electronic structures require large active space wave functions and dynamic correlation effects.
- Existing methods struggle with quantitatively accurate descriptions of magnetic, catalytic, and optical properties.
Purpose of the Study:
- To develop a novel quantum chemistry method for accurate electronic structure modeling.
- To efficiently incorporate dynamic correlation effects beyond large active spaces.
- To improve the description of magnetic, catalytic, and optical properties.
Main Methods:
- Developed Stochastic-SplitGAS, an uncontracted multireference perturbation theory.
- Utilized FCIQMC imaginary-time evolution of effective Hamiltonians.
- Employed generalized active space concept and Löwdin's partitioning technique.
- Stochastically solved an effective Hamiltonian constructed from partitioned configurational interaction space.
Main Results:
- Stochastic-SplitGAS effectively applies perturbative corrections to large active space wave functions.
- The method avoids the bottleneck of high-order reduced density matrices.
- Demonstrated capabilities on Fe(II)-porphyrin and [Fe(III)2S2]2- complex model systems.
Conclusions:
- Stochastic-SplitGAS offers a computationally efficient and accurate approach for electronic structure calculations.
- The method advances the study of systems with many unpaired electrons.
- Provides a pathway for improved understanding of magnetic, catalytic, and optical properties.
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