Energetics of Covalent Bonding from Wave Function Tiles

Area of Science:

• Quantum Chemistry
• Computational Chemistry

Background:

• The driving force behind covalent bonding has been debated for a century.
• While bonding mechanisms for simple systems like H2 are understood, larger systems with C-C bonds remain elusive.

Purpose of the Study:

• To investigate the bond energetics of ethane, a model system for covalent C-C bonds.
• To compare the bonding mechanism in ethane to that of H2.
• To demonstrate the utility of wave function tiles for analyzing complex bonding.

Main Methods:

• Decomposition of the 54-dimensional electronic wave function of ethane using dynamic Voronoi Metropolis sampling.
• Analysis of electron energies as a function of C-C bond length.
• Decomposition of C-C bond energy into kinetic and potential energy terms.

Main Results:

• Electrons within wave function tiles correspond to distinct chemical identities.
• The primary contributors to binding energy are the electron pairs in the C-C bonding region.
• Ethane's bonding energetics mirror H2, showing an initial kinetic energy dip followed by an increase and a decrease in potential energy.
• Bond formation is accompanied by a contraction of C-C bonding electron density.

Conclusions:

• The covalent C-C bond in ethane shares similarities with the H2 bond.
• Wave function tiles offer a versatile method for decomposing covalent bonding energetics in high-dimensional systems.
• The findings provide insight into the fundamental nature of chemical bonding.