Intramolecular symmetry-adapted perturbation theory with a single-determinant wavefunction

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Non-covalent interactions are crucial for molecular structure and function.
• Analyzing intramolecular non-covalent interactions requires specialized computational methods.
• Existing methods may not fully capture the nuances of these interactions within a single molecule.

Purpose of the Study:

• To introduce a novel intramolecular energy decomposition scheme.
• To analyze non-covalent interactions within molecules using a symmetry-adapted perturbation theory (SAPT) framework.
• To provide a detailed description of various intramolecular non-covalent phenomena.

Main Methods:

• Development of the intramolecular symmetry-adapted perturbation theory (intra-SAPT) approach.
• Utilizing the Chemical Hamiltonian and a zeroth-order wavefunction.
• Decomposition of interaction energy into electrostatic-exchange, induction, and dispersion components.

Main Results:

• The intra-SAPT scheme successfully analyzes intramolecular non-covalent interactions.
• A single-determinant wavefunction provides insightful descriptions of hydrogen bonds, dihydrogen contacts, and π - π stacking.
• The method can differentiate between competing intra- and intermolecular interactions.

Conclusions:

• Intramolecular energy decomposition is feasible and insightful.
• Intra-SAPT offers a powerful tool for studying molecular interactions.
• The approach enhances understanding of molecular behavior driven by non-covalent forces.