Calculation of MP2 and coupled-cluster molecular properties using the q-integral method

Area of Science:

• Quantum Chemistry
• Computational Physics

Background:

• Accurate theoretical models are crucial for understanding molecular systems.
• Quantum mechanical calculations provide insights into electronic structure and properties.

Purpose of the Study:

• To apply the q-Integral method for quantum mechanical calculations of the H(2) system.
• To investigate correlation corrections using Møller-Plesset perturbation theory and Coupled-Cluster theory.
• To evaluate key molecular properties including potential energy curves and spectroscopic constants.

Main Methods:

• Utilized the q-Integral method for ab initio quantum chemistry calculations.
• Incorporated correlation corrections via Møller-Plesset second-order perturbation (MP(2)) and Coupled-Cluster (CC) theory.
• Employed STO-3G, STO-6G, and double-zeta (DZV) atomic basis sets.
• Implemented the q-Integral method within the GAMESS quantum chemistry package.

Main Results:

• Calculated potential energy curves for the H(2) system.
• Determined rovibrational spectroscopy constants and spectra.
• Evaluated the interatomic equilibrium distance.
• Computed longitudinal static hyper(polarizability).

Conclusions:

• The q-Integral method, with correlation corrections, provides a robust approach for H(2) system calculations.
• The study successfully determined essential molecular properties, validating the computational method.
• Results offer valuable data for further theoretical and experimental investigations of diatomic molecules.