Fast Switching Alchemical Transformations in Molecular Dynamics Simulations.

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Accurate calculation of free energies is crucial for understanding molecular interactions.
• Alchemical free energy methods are powerful but can be computationally intensive.
• Smooth Particle Mesh Ewald (SPME) is an efficient method for electrostatic interactions.

Purpose of the Study:

• To present an efficient and rigorous implementation of fast switching alchemical transformations.
• To apply this method to calculate 1-octanol/water partition coefficients.
• To compare the accuracy and efficiency against traditional methods.

Main Methods:

• Utilized fast switching alchemical transformations with SPME for electrostatics.
• Employed bidirectional nonequilibrium alchemical trajectories.
• Applied the Crooks fluctuation theorem and Bennett acceptance ratio.

Main Results:

• Successfully computed free energies for selected organic molecules.
• Evaluated 1-octanol/water partition coefficients.
• Demonstrated competitive accuracy and efficiency compared to traditional methods.

Conclusions:

• The fast switching alchemical transformation is a viable and efficient method for free energy calculations.
• This approach offers a competitive alternative to traditional equilibrium simulation methods.
• The implementation is suitable for determining partition coefficients and other molecular properties.