Progress in calculating the potential energy surface of H3+

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Spectroscopy

Background:

• Accurate electronic structure calculations are crucial for understanding molecular properties.
• Traditional methods often struggle with electron correlation, limiting accuracy.
• The H(3)(+) ion is a fundamental system in astrochemistry and molecular physics.

Purpose of the Study:

• To develop and apply a highly accurate method for calculating the potential energy surface (PES) of the H(3)(+) ion.
• To utilize explicitly correlated Gaussians with inter-electron distances for improved accuracy.
• To reproduce the experimental rovibrational spectrum of H(3)(+) with high precision.

Main Methods:

• Employed wave function expansions using explicitly correlated Gaussian basis functions, incorporating inter-electron distances.
• Utilized analytical energy gradients for efficient minimization of the Rayleigh-Ritz variational energy functional.
• Incorporated adiabatic, relativistic corrections, and effective accounting of non-adiabatic effects.

Main Results:

• A highly accurate potential energy surface (PES) for the H(3)(+) ion was computed.
• The computational procedure effectively eliminated linear dependencies and adapted Gaussian centers to molecular geometry.
• The calculated rovibrational spectrum of H(3)(+) matched experimental data with 0.1 cm⁻¹ accuracy up to 16,600 cm⁻¹ above the ground state.

Conclusions:

• Explicitly correlated Gaussians with inter-electron distances provide a robust method for accurate electronic structure calculations.
• The developed computational approach enables precise prediction of molecular spectra.
• This work significantly advances the understanding and computational treatment of the H(3)(+) ion.