Configuration selection within vibrational multiconfiguration self-consistent field theory: application to bridged...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Spectroscopy

Background:

• Vibrational multiconfiguration self-consistent field (VMC) calculations are computationally intensive.
• Accurate prediction of molecular vibrational transitions is crucial for understanding chemical properties and reactions.

Purpose of the Study:

• To develop and validate a configuration selection scheme to accelerate VMC calculations.
• To apply the accelerated method to determine accurate vibrational transitions for bridged lithium compounds.

Main Methods:

• Implementation of a configuration selection scheme within the VMC framework.
• High-level coupled-cluster calculations were used to generate potential energy surfaces.
• Application to Li(2)H(2), Li(2)F(2), Li(2)O(2), and Li(3)F(3) systems.

Main Results:

• The configuration selection scheme achieved an acceleration of approximately two orders of magnitude.
• Deviations from reference calculations were found to be negligible.
• Accurate vibrational transition frequencies were obtained for all fundamental modes of the studied lithium compounds.

Conclusions:

• The developed configuration selection scheme is a highly efficient and accurate approach for VMC calculations.
• The method enables precise prediction of vibrational spectra for complex molecular systems.
• The importance of including 4-mode couplings was highlighted for specific systems like Li(2)H(2).