Molecule-Environment Embedding with Quantum Monte Carlo: Electrons Interacting with Drude Oscillators.

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• Accurate modeling of molecular systems requires accounting for electronic interactions and environmental effects.
• The El-QDO method embeds electronic systems within a bath of quantum harmonic oscillators (quantum Drude oscillators, QDOs).

Purpose of the Study:

• To comprehensively investigate and validate the El-QDO embedding method.
• To analyze short-range regularization functions for electron-QDO interactions.
• To assess the accuracy of El-QDO for solvation energies and many-body interactions.

Main Methods:

• Development and implementation of the El-QDO Hamiltonian and ansatz.
• Application of quantum Monte Carlo (QMC) algorithms for electronic and drudonic degrees of freedom.
• Benchmarking regularization functions on argon and water dimers.
• Application to benzene and water dimer solvation energies.

Main Results:

• Analysis of short-range regularization functions resolved overpolarization errors.
• El-QDO accurately predicted solvation energies for benzene and water dimers, matching ab initio calculations.
• Demonstrated explicit many-body treatment of electrostatic, polarization, and dispersion interactions.

Conclusions:

• The El-QDO method provides an accurate and efficient approach for modeling electronic systems interacting with a quantum harmonic oscillator environment.
• The method successfully captures complex many-body interactions crucial for understanding solvation and material properties.
• El-QDO offers a robust computational tool for advanced chemical and materials simulations.