Polarizable Charge Equilibration Model for Transition-Metal Elements.

Area of Science:

• Computational materials science
• Quantum chemistry
• Solid-state physics

Background:

• The polarizable charge equilibration (PQEq) method offers a simplified yet precise approach to modeling electrostatic interactions and polarization effects in materials.
• Previous work focused on optimizing PQEq parameters for main group elements.

Purpose of the Study:

• To extend the PQEq method by optimizing parameters for 24 d-block transition metals (TM).
• To validate the accuracy of the PQEq method for TM by comparing its results with quantum mechanics (QM) calculations.
• To assess the PQEq method's performance across various oxidation states and coordination environments relevant to TM compounds.

Main Methods:

• Optimization of PQEq parameters (electronegativity, hardness, atomic radius, and spring constant) for 24 transition metal elements.
• Validation against QM interaction energies and induced fields for 24 molecular clusters representing TM oxides and other compounds.
• Analysis of charge distributions in relation to coordination number and oxidation states.

Main Results:

• Original electronegativity (χ) and hardness (J) parameters remain valid for TM ionization.
• Atomic radius parameter requires adjustment to experimental ionic radii for TM.
• An increased spring constant is necessary to accurately describe atomic polarizability in TM.
• Optimized PQEq parameters yield accurate interaction energies and realistic charge distributions compared to QM.

Conclusions:

• The refined PQEq method provides an accurate description of electrostatic interactions and polarization for transition metals.
• The optimized parameters enable reliable molecular dynamics simulations for inorganic and organometallic materials containing TM.
• PQEq's ability to capture oxidation state and coordination dependencies enhances its utility in materials modeling.