Fast Approximate but Accurate QM/MM Interactions for Polarizable Embedding.

Area of Science:

• Computational Chemistry
• Spectroscopy
• Quantum Mechanics/Molecular Mechanics (QM/MM)

Background:

• The interface between quantum (QM) and molecular mechanics (MM) regions presents a significant computational challenge in polarizable QM/MM methods.
• This computational bottleneck hinders the application of these methods in areas like computational spectroscopy.

Purpose of the Study:

• To investigate and develop efficient approximations for the QM/MM coupling in polarizable QM/MM calculations.
• To assess the accuracy and computational speed of these new strategies for spectroscopic property calculations.

Main Methods:

• Exploration of three distinct approximation strategies for QM/MM coupling.
• Utilized multipole expansion techniques to implement the approximations.
• Benchmarked implementations against established methods for accuracy and computational efficiency.

Main Results:

• The proposed approximation strategies offer substantial computational savings.
• Accuracy of calculated spectroscopic properties, including one- and two-photon absorption strengths, is maintained.
• Demonstrated the viability of these approximations for computational spectroscopy.

Conclusions:

• The developed multipole expansion-based approximations effectively address the QM/MM coupling bottleneck.
• These strategies provide a computationally efficient alternative for polarizable QM/MM methods in spectroscopy.
• Significant speed-up is achievable without compromising the predictive power for spectroscopic properties.