Smolyak Algorithm Adapted to a System-Bath Separation: Application to an Encapsulated Molecule with Large-Amplitude...

Area of Science:

• Quantum chemistry
• Computational physics
• Molecular dynamics

Background:

• Rigorous quantum simulations are crucial for understanding molecular behavior.
• Standard Smolyak algorithms face convergence challenges, limiting simulations of complex systems.
• Simulating floppy molecules and their interactions requires advanced computational techniques.

Purpose of the Study:

• To develop an adapted Smolyak algorithm for efficient and rigorous quantum simulations.
• To overcome the convergence limitations of standard Smolyak methods.
• To enable accurate simulations of large, floppy molecules and their environments.

Main Methods:

• Adaptation of the Smolyak algorithm incorporating system-bath separation.
• Utilizing a sparse grid method within a specific Hamiltonian configuration.
• Applying the method to simulate hydrogen (H2) molecules within sII clathrate hydrates.

Main Results:

• Achieved highly efficient convergence for excitation transitions in the 'system' part.
• Successfully simulated floppy molecules with over a hundred degrees of freedom.
• Confirmed triplet splittings for translational and rotational transitions of H2.
• Observed a slight increase in translational transitions compared to rigid cage models.

Conclusions:

• The adapted Smolyak algorithm offers a general solution to convergence problems in quantum simulations.
• This method facilitates the simulation of complex systems like floppy molecules in clathrate hydrates.
• The findings provide accurate insights into the quantum dynamics of H2 within its hydrate cage.