Linked coupled cluster Monte Carlo

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Theoretical Chemistry

Background:

• Stochastic coupled cluster (CC) methods offer a computationally tractable approach to electronic structure calculations.
• Conventional deterministic CC methods face limitations in treating large systems due to high computational scaling.
• Accurate representation of the electronic wavefunction is crucial for reliable quantum chemical predictions.

Purpose of the Study:

• To introduce a novel formulation of the stochastic coupled cluster (SCC) method.
• To investigate the impact of improved wavefunction representation granularity on computational cost.
• To assess the applicability of the new method to larger systems and higher excitation levels.

Main Methods:

• Development of a new SCC formulation utilizing a similarity transformed Hamiltonian.
• Systematic analysis of wavefunction sampling requirements across various molecular systems.
• Evaluation of computational cost reduction as a function of wavefunction representation granularity.

Main Results:

• The new SCC formulation demonstrates a reduction in the critical population needed for accurate wavefunction sampling.
• Improved granularity in wavefunction representation leads to substantial decreases in computational expense.
• The method shows efficacy for a range of systems and excitation levels, outperforming conventional approaches.

Conclusions:

• The enhanced SCC method significantly lowers computational demands, making larger quantum chemical problems tractable.
• This development broadens the scope of stochastic coupled cluster methods, enabling studies of previously inaccessible systems.
• The approach holds promise for advancing quantum chemistry calculations in various scientific domains.