Spectroscopy of H3+ based on a new high-accuracy global potential energy surface

Area of Science:

• Quantum Chemistry
• Molecular Spectroscopy
• Computational Physics

Background:

• The hydrogen ion H(3)(+) is a fundamental molecular system for testing quantum mechanical calculations.
• Accurate theoretical predictions of its ro-vibrational spectrum are crucial for benchmarking computational methods.
• Previous calculations faced limitations in accuracy and global potential energy surface (PES) representation.

Purpose of the Study:

• To present a new, highly accurate global potential energy surface (PES) for H(3)(+).
• To compute the ro-vibrational spectrum of H(3)(+) using the new PES and advanced theoretical methods.
• To validate the computational accuracy by comparing with recent experimental measurements.

Main Methods:

• Ab initio quantum mechanical calculations to generate accurate points for the PES.
• Development of an analytical representation for the global PES.
• Inclusion of relativistic, adiabatic, and non-adiabatic effects in spectral computations.
• Comparison of computed transition frequencies with experimental data in visible and infrared regions.

Main Results:

• A new global PES for H(3)(+) was constructed with high accuracy (0.01 cm(-1) relative to non-relativistic limit).
• The analytical PES representation shows a standard deviation of 0.097 cm(-1).
• Computed ro-vibrational transition frequencies achieve an accuracy of approximately 0.1 cm(-1), matching experimental data.
• The accuracy facilitated the reassignment of some measured spectral lines, improving agreement between theory and experiment.

Conclusions:

• The developed global PES and advanced computational methods provide highly accurate ro-vibrational spectra for H(3)(+).
• The study demonstrates the importance of including various quantum effects for precise molecular ion spectroscopy.
• The refined theoretical predictions and reassignment of experimental lines advance our understanding of H(3)(+) spectroscopy.