Position-Dependent Diffusion Constant of Molecules in Heterogeneous Systems as Evaluated by the Local Mean Squared...

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Materials Science

Background:

• Accurate calculation of diffusion constants is crucial for understanding molecular dynamics.
• Heterogeneous systems present challenges for traditional diffusion analysis methods.
• Existing methods may struggle with position-dependent diffusion phenomena.

Purpose of the Study:

• To introduce a novel method for evaluating position-dependent diffusion constants.
• To establish the accuracy of the new method in homogeneous systems.
• To demonstrate the method's applicability to complex heterogeneous systems.

Main Methods:

• Utilizing an additional flat-bottom potential to identify unperturbed trajectory segments.
• Analyzing these segments to determine the position-dependent diffusion constant.
• Comparing the novel method with established conventional techniques.

Main Results:

• The method's accuracy was validated against the Einstein relation in homogeneous systems.
• Successful application demonstrated for a hydrophobic solute near a hydrophobic wall.
• Significant improvements and advantages over conventional methods were illustrated.

Conclusions:

• The proposed method provides a powerful and accurate approach for calculating diffusion constants.
• It is particularly useful for studying kinetics in heterogeneous systems using molecular dynamics.
• This technique offers a valuable tool for advancing the understanding of molecular behavior in complex environments.