Gaussian-based multiconfiguration time-dependent Hartree: a two-layer approach. I. Theory.

Area of Science:

• Quantum chemistry and theoretical physics
• Computational methods for quantum dynamics

Background:

• The Gaussian-based multiconfiguration time-dependent Hartree (G-MCTDH) method is crucial for simulating quantum dynamics.
• Standard G-MCTDH faces performance and convergence limitations due to the computational cost of evolving multi-dimensional frozen Gaussians (FGs).

Purpose of the Study:

• To introduce a novel two-layer variant of the G-MCTDH approach.
• To enhance the performance and convergence properties of quantum propagation.
• To alleviate computational bottlenecks in G-MCTDH and variational multiconfigurational Gaussian (vMCG) methods.

Main Methods:

• Developed a two-layer G-MCTDH variant.
• Combines factorizable multi-dimensional FGs into flexible, MCTDH-like single-particle functions.
• Reduces the variational evolution of Gaussian parameters to low-dimensional subspaces.

Main Results:

• The novel scheme significantly improves performance and convergence properties.
• Effectively alleviates computational bottlenecks in G-MCTDH and vMCG.
• Orthogonal first-layer single-particle functions allow straightforward integration with existing multi-layer MCTDH schemes.

Conclusions:

• The proposed two-layer G-MCTDH variant offers a significant advancement in quantum dynamics simulations.
• The method provides a more efficient and accurate approach to quantum propagation.
• Its compatibility with multi-layer MCTDH schemes broadens its applicability.