Optimizing molecular properties using a relative index of thermodynamic stability and global optimization techniques

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Optimizing molecular properties requires considering both geometry and chemical composition.
• Accurate energy comparisons between different chemical species are crucial for stability assessments.

Purpose of the Study:

• To develop a global optimization (GO) strategy for molecular property optimization.
• To introduce a relative index of thermodynamic stability (RITS) for meaningful energy comparisons.
• To ensure thermodynamic stability in optimized molecular solutions.

Main Methods:

• A global optimization (GO) strategy was devised.
• A relative index of thermodynamic stability (RITS) was introduced.
• Objective functions (F) were defined using RITS and other properties.
• Calculations were performed using Kohn-Sham Density Functional Theory (KS-DFT).

Main Results:

• The GO strategy successfully identified known stable molecules (e.g., N2, CO2, acetic acid) within the CmHnNpOq system.
• GO accurately predicted low-energy structures for CumSnn (+) clusters, matching previous separate optimizations.
• Seven bimetallic clusters (AmBn) with energy gaps (Eg) greater than 1.5 eV were discovered.

Conclusions:

• The developed GO strategy is effective for discovering stable molecular compositions and configurations.
• Incorporating RITS into the objective function ensures thermodynamically stable solutions.
• This approach accelerates the discovery of molecules and materials with desired properties.