Energy, Structures, and Response Properties with a Fully Coupled QM/AMOEBA/ddCOSMO Implementation.

Area of Science:

• Computational Chemistry
• Molecular Modeling
• Biophysics

Background:

• Accurate simulation of large, complex biological systems requires efficient computational methods.
• Polarization effects are critical for understanding molecular interactions and properties in biological environments.
• Existing quantum mechanics/molecular mechanics (QM/MM) models often struggle with scalability and accurate environmental representation.

Purpose of the Study:

• To implement and validate a fully coupled polarizable QM/MM/continuum model.
• To assess the computational efficiency and scalability of the model for large systems.
• To investigate the impact of polarization and continuum models on calculated properties.

Main Methods:

• Development of a QM/MM/continuum model using the AMOEBA polarizable force field.
• Integration with a domain decomposition implementation of the conductor-like screening model.
• Calculation of energies, response properties, and analytical gradients.
• Application to three variants of green-fluorescent protein to study computational cost and convergence.

Main Results:

• The implemented model exhibits linear scaling in memory and computational cost with system size.
• Demonstrated the fundamental importance of polarization effects by comparing polarizable and nonpolarizable embeddings.
• Analyzed the influence of the continuum model on property convergence concerning embedding size.

Conclusions:

• The developed polarizable QM/MM/continuum model is suitable for simulating large, complex biological systems efficiently.
• Polarization effects significantly impact the accuracy of computed properties in QM/MM calculations.
• The model provides a robust framework for future investigations of molecular mechanisms in biological contexts.