HF Trimer: A New Full-Dimensional Potential Energy Surface and Rigorous 12D Quantum Calculations of Vibrational...

Area of Science:

• Chemical Physics
• Quantum Chemistry
• Spectroscopy

Background:

• The hydrogen fluoride (HF) trimer is a fundamental model for studying hydrogen-bonded networks.
• Previous theoretical models of HF trimer vibrations showed good agreement with experimental data but required improvement.
• A more accurate 12-dimensional potential energy surface (PES) was needed for precise theoretical investigations.

Purpose of the Study:

• To develop the first fully ab initio 12-dimensional PES for the hydrogen fluoride (HF) trimer.
• To improve the accuracy of theoretical calculations for the structure, energetics, spectroscopy, and dynamics of HF trimers.
• To provide a more reliable theoretical tool for understanding hydrogen-bond networks.

Main Methods:

• Ab initio electronic structure calculations were performed for approximately 42,540 geometries at the CCSD(T)-F12a/AVTZ level.
• A permutationally invariant polynomial-neural network based Δ-machine learning approach was used for efficient basis-set-superposition error (BSSE) correction.
• The fitting error of the final PES was minimized to 0.035 kcal/mol.

Main Results:

• A new, high-precision 12D PES for the HF trimer was successfully constructed.
• The PES incorporates BSSE correction through a cost-efficient machine learning approach.
• Quantum calculations using the new PES showed significantly improved agreement with experimental spectroscopic data.

Conclusions:

• The developed fully ab initio 12D PES represents a significant advancement for theoretical studies of HF trimers.
• This accurate PES will enable more precise investigations into the vibrational dynamics and spectroscopy of hydrogen-bonded systems.
• The methodology employed offers a cost-efficient route to high-accuracy PES construction for molecular clusters.