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Stochastic coupled cluster theory: Efficient sampling of the coupled cluster expansion
Charles J C Scott1, Alex J W Thom1
1Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
The Journal of Chemical Physics
|October 2, 2017
Summary
New methods for stochastic coupled cluster theory improve calculation stability and reduce costs. These approaches enhance the sampling of coupled cluster expansions, particularly at higher excitation levels.
Area of Science:
- Quantum Chemistry
- Computational Chemistry
- Theoretical Chemistry
Background:
- Stochastic coupled cluster theory is essential for quantum chemical calculations.
- Previous methods faced limitations due to the non-linear nature of coupled cluster wavefunctions.
- Efficient sampling is crucial for the scalability of these methods.
Purpose of the Study:
- To address limitations in stochastic coupled cluster theory sampling.
- To propose novel, stable, and cost-effective sampling strategies.
- To improve the accuracy and efficiency of coupled cluster calculations.
Main Methods:
- Developed new sampling approaches for coupled cluster expansions.
- Introduced 'even' and 'truncated' selections for sampling weights and cluster operators.
- Applied these modifications to stochastic coupled cluster calculations.
Main Results:
- Achieved dramatically improved calculation stability.
- Demonstrated significant reductions in computational and memory costs.
- Showcased effectiveness at higher truncation levels, reducing terms by up to 98%.
Conclusions:
- The proposed 'even' and 'truncated' selection methods enhance stochastic coupled cluster theory.
- These modifications offer a more stable and efficient approach to quantum chemical calculations.
- The methods are particularly beneficial for calculations involving high excitation levels.
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