The adaptive buffered force QM/MM method in the CP2K and AMBER software packages

Area of Science:

• Computational chemistry
• Molecular modeling
• Quantum mechanics/molecular mechanics (QM/MM)

Background:

• Accurate simulation of complex chemical systems requires robust QM/MM methods.
• Existing QM/MM approaches often face challenges with interface errors and computational stability.
• The adaptive buffered force (AdBF) method offers a potential solution to these limitations.

Purpose of the Study:

• To implement and validate the adaptive buffered force (AdBF) QM/MM method in CP2K and AMBER.
• To assess the performance of AdBF in simulating various chemical systems, including bulk water and hydrolysis reactions.
• To compare AdBF with other QM/MM variants and fully QM simulations.

Main Methods:

• Implementation of AdBF QM/MM with redefinable QM/MM regions and buffered force-mixing.
• Development of new adaptive thermostats to support force-mixing methods.
• Benchmarking using simulations of bulk water, water autoprotolysis, and dimethyl-phosphate hydrolysis.
• Utilizing semiempirical Hamiltonians and density functional theory for QM calculations.

Main Results:

• AdBF QM/MM accurately reproduces the structure and energetics of the QM region, matching fully QM simulations.
• Suitable parameterization based on force convergence tests is crucial for AdBF accuracy.
• Adaptive unbuffered force-mixing and conventional QM/MM methods showed potential but were prone to instabilities.

Conclusions:

• The AdBF QM/MM scheme provides a reliable and accurate method for computational chemistry simulations.
• AdBF effectively minimizes QM/MM interface errors, enhancing simulation stability and accuracy.
• This implementation offers a valuable tool for studying complex chemical processes at the molecular level.