Approximate Quantum Dynamics using Ab Initio Classical Separable Potentials: Spectroscopic Applications.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Dynamics

Background:

• Quantum molecular dynamics simulations are crucial for understanding chemical reactions.
• Existing ab initio methods can be computationally expensive for large systems.

Purpose of the Study:

• To introduce a novel, approximate algorithm for ab initio quantum molecular dynamics.
• To develop a method scalable for large molecular systems.

Main Methods:

• The ab initio classical separable potentials (AICSP) method is proposed.
• It utilizes mean-field potentials derived from classical ab initio molecular dynamics.
• The nuclear wave function is propagated using "on the fly" generated effective potentials.

Main Results:

• AICSP accurately calculates stationary anharmonic frequencies of hydrogen stretching modes.
• The method shows good agreement with experimental data for amino acids and nucleobases.
• Favorable scaling with the number of vibrational modes was demonstrated.

Conclusions:

• The AICSP method offers a computationally efficient approach for quantum molecular dynamics.
• It is applicable to large molecules, including peptides and biological systems.
• Future work will explore its use for vibrational line widths and shapes.