Interpretation and Automatic Generation of Fermi-Orbital Descriptors

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Fermi-orbital descriptors (FODs) are proposed as carriers of chemical bonding information.
• Existing methods for determining FOD positions can be computationally intensive or lack general accessibility.

Purpose of the Study:

• To interpret Fermi-orbital descriptors (FODs) and demonstrate their chemical bonding significance.
• To validate FOD-derived bond orders against established values.
• To explore and propose accessible methods for generating FOD positions.

Main Methods:

• Interpretation of Fermi-orbital descriptors (FODs) for chemical bonding insights.
• Calculation of bond orders from FODs and comparison with reference values.
• Analysis of optimized FOD positions within the Fermi-Löwdin orbital self-interaction correction (FLO-SIC) method.
• Testing computational independence using Local Spin Density Approximation, PBE GGA, and SCAN meta-GGA functionals.
• Development and discussion of four novel methods for FOD generation: electron force field, orbital density centers of mass, Monte Carlo algorithm, and Lewis-like bonding approach.

Main Results:

• FODs effectively encode chemical bonding information.
• Derived bond orders show strong agreement with reference values.
• Optimized FOD positions in FLO-SIC correlate with Linnett's double-quartet theory, an extension of Lewis theory.
• This correlation is robust across different exchange-correlation functionals.
• Four distinct and accessible methods for generating FOD positions are presented and evaluated.

Conclusions:

• Fermi-orbital descriptors provide valuable insights into chemical bonding.
• The Fermi-Löwdin orbital self-interaction correction method, utilizing FODs, aligns with established chemical bonding theories.
• The proposed methods enhance the accessibility and applicability of FODs in computational chemistry research.
• These findings pave the way for future developments in FLO-SIC and related electronic structure theories.