Efficient vibrationally correlated calculations using n-mode expansion-based kinetic energy operators

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Modeling

Background:

• The n-mode expansion is widely used for representing molecular potential energy surfaces in quantum chemical simulations due to its efficiency and flexibility.
• Kinetic energy operators are crucial for accurate molecular simulations but can be complex, especially in generalized coordinate systems.

Purpose of the Study:

• To investigate the performance of n-mode expansion-based kinetic energy operator models in polyspherical coordinates.
• To assess the accuracy of these models in vibrationally correlated calculations and their impact on potential energy surface construction.
• To introduce a workflow for generating n-mode expanded kinetic energy operators on-the-fly.

Main Methods:

• Implementation and testing of n-mode expansion-based kinetic energy operators.
• Vibrational correlation calculations.
• Adaptive density guided approach for potential energy surface construction.

Main Results:

• n-mode expansion-based kinetic energy operators are reliable and systematically improvable approximations of the full kinetic energy operator.
• These models demonstrate good accuracy in vibrationally correlated calculations.
• The proposed on-the-fly generation workflow integrates seamlessly with the adaptive density guided approach.

Conclusions:

• n-mode expansion-based kinetic energy operators offer a robust and improvable approach for quantum chemical simulations.
• The developed workflow enables the study of systems and coordinate systems lacking analytical kinetic energy operator forms.
• This methodology enhances the flexibility and applicability of quantum chemical simulations.