Tethered Gaussian wavepackets for quantum dynamics simulations: Sticking together for better convergence

Area of Science:

• Computational Chemistry
• Quantum Dynamics
• Theoretical Physics

Background:

• Standard Gaussian products are common for representing potential energy surfaces (PESs) and wavefunctions.
• Basis set size requirements increase significantly with dimensionality, impacting computational efficiency.

Purpose of the Study:

• To develop novel Gaussian basis sets for improved accuracy and efficiency in high-dimensional quantum simulations.
• To enhance the representation of potential energy surfaces and time-dependent wavefunctions.

Main Methods:

• Recasting Gaussian basis functions into an "additive" form for PES regression.
• Proposing and implementing "stretched" and "tethered" Gaussian wavepacket (GWP) basis functions for quantum dynamics.
• Evaluating convergence of time-dependent observables with new GWP basis sets.

Main Results:

• Additive Gaussian basis functions improve fitting convergence for higher-dimensional PES regression.
• Tethered GWP basis sets demonstrate improved convergence for time-dependent observables compared to standard GWPs.
• The proposed GWP basis sets are compatible with existing GWP-based quantum dynamics methods.

Conclusions:

• Novel GWP basis sets offer a pathway to more accurate quantum dynamics predictions.
• The new basis sets enable the use of smaller basis sets for achieving higher accuracy in high-dimensional systems.
• This work enhances the applicability of Gaussian-based methods in complex quantum simulations.