Analytical energy gradients for local second-order Møller-Plesset perturbation theory using density fitting...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Accurate calculation of energy derivatives is crucial for understanding molecular properties and reaction mechanisms.
• Second-order Møller-Plesset perturbation theory (MP2) provides a balance of accuracy and computational cost for electronic structure calculations.
• Scaling limitations of traditional MP2 methods hinder their application to large molecular systems.

Purpose of the Study:

• To develop an efficient method for computing analytical energy derivatives for local MP2.
• To leverage density fitting approximations to reduce computational scaling.
• To enable accurate calculations for larger molecules and basis sets.

Main Methods:

• Implementation of analytical energy derivative calculations using local second-order Møller-Plesset perturbation theory.
• Application of density fitting approximations for all four-index integrals and their derivatives.
• Utilizing local fitting approximations to achieve favorable computational scaling.

Main Results:

• Achieved quadratic scaling with molecular size and cubic scaling with basis set size.
• Demonstrated negligible impact of density fitting on the accuracy of optimized structures and energy differences.
• Successfully applied the method to large organic molecules and molecular clusters, including geometry optimizations of systems with over 100 atoms and 2000 basis functions.

Conclusions:

• The developed method offers significant computational efficiency improvements for local MP2 energy derivative calculations.
• The approach allows for the study of much larger systems than previously feasible with MP2 gradient programs.
• The method provides an accurate and efficient tool for computational chemistry research.