An Efficient Approach for Studies of Water Clusters Using Diffusion Monte Carlo.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Molecular Modeling

Background:

• Studying molecular clusters like water requires accurate quantum mechanical methods.
• Traditional diffusion Monte Carlo (DMC) can be computationally intensive for complex systems.

Purpose of the Study:

• To develop and validate an efficient hybrid diffusion Monte Carlo (DMC) approach for molecular clusters.
• To investigate the properties of small water clusters (n=1, 2, 3) using this novel method.

Main Methods:

• A hybrid DMC approach combining importance sampling for intramolecular degrees of freedom and unguided DMC for intermolecular interactions.
• Application to water monomers, dimers, and trimers, including nine isotopologues of the water trimer.

Main Results:

• The hybrid DMC method significantly reduces simulation size for converged zero-point energies and ground state wave functions.
• Demonstrated efficiency and accuracy in characterizing the low-energy minima landscape of water trimers.

Conclusions:

• The hybrid DMC approach offers a computationally advantageous alternative for studying molecular clusters.
• This method provides insights into the conformational sampling of water clusters on their potential energy surfaces.