Spectroscopic data for the LiH molecule from pseudopotential quantum Monte Carlo calculations

Area of Science:

• Computational chemistry
• Quantum mechanics
• Molecular physics

Background:

• Pseudopotential models are essential for simplifying electronic structure calculations of molecules.
• Accurate interatomic potentials are vital for understanding molecular properties and reactions.
• Lithium hydride (LiH) serves as a fundamental system for testing theoretical models.

Purpose of the Study:

• To investigate the accuracy of pseudopotential models for the lithium hydride (LiH) molecule.
• To evaluate the impact of core polarization potentials on calculated interatomic potentials.
• To determine the significance of core-valence correlation and core relaxation effects.

Main Methods:

• Utilized Quantum Monte Carlo (QMC) and quantum chemistry techniques.
• Calculated interatomic potentials for LiH.
• Compared calculated spectroscopic constants and well depth with experimental data.
• Tested two newly developed pseudopotentials and investigated Li core polarization effects.

Main Results:

• Calculations achieved high accuracy, enabling the isolation of errors from pseudopotentials and core polarization.
• The study identified core-valence correlation as a significant factor influencing the interatomic potential.
• Core relaxation effects were also found to be important in determining the interatomic potential of LiH.

Conclusions:

• Pseudopotential models require careful consideration of core-valence correlation and core relaxation for accurate LiH interatomic potentials.
• The tested pseudopotentials and core polarization models provide insights into their suitability for such calculations.
• This work contributes to the refinement of theoretical methods for studying small molecules.