Analytic Computation of Vibrational Circular Dichroism Spectra Using Second-Order Møller-Plesset Perturbation Theory.

Area of Science:

• Quantum Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Vibrational Circular Dichroism (VCD) spectroscopy is a powerful tool for determining molecular chirality.
• Accurate theoretical prediction of VCD spectra requires sophisticated computational methods.
• Previous methods for calculating VCD properties, particularly at correlated levels of theory like MP2, were computationally intensive.

Purpose of the Study:

• To develop and implement an analytic-derivative-based formulation for VCD atomic axial tensors within second-order Møller-Plesset (MP2) perturbation theory.
• To validate the new analytic formulation by comparing its results with a finite-difference approach.
• To assess the computational efficiency of the analytic method compared to numerical differentiation.

Main Methods:

• Formulation of analytic-derivative expressions for VCD atomic axial tensors at the MP2 level.
• Implementation of the analytic method in a quantum chemistry framework.
• Comparison of results with a previously reported finite-difference (numerical) method.
• Calculation of the VCD spectrum for (S)-methyloxirane using the new analytic MP2 approach.

Main Results:

• Successful derivation and implementation of the first analytic-derivative-based VCD atomic axial tensors for MP2 theory.
• Close agreement between the analytic formulation and the finite-difference approach, confirming the accuracy of the new method.
• Demonstrated significant reduction in computational cost for the analytic method compared to the numerical derivative approach, with improved computational scaling.
• Reported the first fully analytic VCD spectrum for (S)-methyloxirane at the MP2 level of theory.

Conclusions:

• The analytic-derivative approach for VCD atomic axial tensors at the MP2 level is accurate and validated.
• This new formulation offers a computationally efficient alternative to numerical methods for VCD calculations.
• The method enables more accessible and accurate theoretical prediction of VCD spectra, aiding in chiral molecule analysis.