Surface Adsorption from the Exchange-Hole Dipole Moment Dispersion Model

Area of Science:

• Computational Chemistry
• Materials Science
• Surface Science

Background:

• Accurate calculation of intermolecular interaction energies is vital in density functional theory.
• Long-range, nonlocal dispersion correlation must be included for precise energy calculations.
• Modeling molecular adsorption on surfaces requires robust theoretical methods.

Purpose of the Study:

• To evaluate the effectiveness of the exchange-hole dipole moment (XDM) dispersion correction for modeling molecular surface adsorption.
• To compute and analyze adsorption energies of aromatic molecules and DNA nucleobases on coinage metal surfaces.
• To assess the accuracy and applicability of the XDM method in surface chemistry.

Main Methods:

• Density functional theory (DFT) calculations.
• Application of the exchange-hole dipole moment (XDM) dispersion correction.
• Calculation of adsorption energies for small aromatic molecules and DNA nucleobases on Cu, Ag, and Au (111) surfaces.
• Utilizing the B86bPBE functional in conjunction with XDM.
• Employing the noncovalent interaction (NCI) plot technique.

Main Results:

• The XDM correction achieved a mean absolute error of 0.04 eV for benzene adsorption on metal surfaces.
• Computed binding energies for other aromatic molecules were within 0.09 eV of experimental data, below typical uncertainties.
• The XDM method demonstrated good performance without requiring modifications to its standard implementation.
• The B86bPBE-XDM combination proved effective for studying surface chemistry.
• The NCI plot technique successfully detected adsorption effects in real space.

Conclusions:

• The XDM dispersion correction is a reliable and accurate method for calculating molecular adsorption energies on metal surfaces.
• The B86bPBE-XDM functional is a strong candidate for computational studies of surface chemistry.
• The XDM method's success is linked to the behavior of the exchange hole, offering insights into dispersion interactions.
• The NCI plot technique provides a valuable real-space visualization of adsorption phenomena.