Direct product-type grid representations for angular coordinates in extended space and their application in the MCTDH...

Area of Science:

• Quantum Chemistry
• Computational Physics
• Theoretical Chemistry

Background:

• Multi-configurational time-dependent Hartree (MCTDH) calculations accurately simulate quantum dynamics.
• Current methods using correlation discrete variable representation (DVR) face challenges with singularities in polar and azimuthal angles within the kinetic energy operator.

Purpose of the Study:

• Introduce a novel direct product-type DVR for arbitrary polar and azimuthal angles.
• Address singularities in the kinetic energy operator for improved quantum dynamics simulations.
• Enhance the efficiency of MCTDH calculations.

Main Methods:

• Developed a new DVR by extending the coordinate space for polar angles to [-π, π].
• Applied the new DVR within MCTDH calculations for the F·CH4 complex.
• Compared the new scheme to the cot-DVR approach.

Main Results:

• The extended space DVR effectively resolves singularities without increasing spectral width.
• MCTDH calculations using the new scheme show more efficient integration of equations of motion.
• Achieved approximately an order of magnitude reduction in central processing unit (CPU) times.

Conclusions:

• The new DVR scheme offers a significant improvement for simulating quantum dynamics with MCTDH.
• This method provides a more efficient and computationally less expensive alternative to previous approaches.
• The findings are crucial for advancing high-dimensional quantum dynamics simulations.