Local electric dipole moments: A generalized approach

Area of Science:

• Computational chemistry
• Molecular modeling
• Physical chemistry

Background:

• Local electric dipole moments are crucial for understanding molecular interactions and properties.
• Traditional methods for calculating these moments are often origin-dependent, limiting their applicability.
• Existing approaches using Bader's atoms-in-molecules (AIM) partitioning rely on bond critical points (BCPs), which are not always computationally feasible or present.

Purpose of the Study:

• To develop an origin-independent method for calculating local electric dipole moments of molecular fragments.
• To provide a more robust and versatile approach applicable to various computational schemes and molecular systems.

Main Methods:

• Derived a definition for fragment dipole moments using internal reference points, avoiding origin-dependence.
• Replaced bond critical points (BCPs) with a minimal set of reference points located between fragments.
• The method is compatible with AIM implementations and other local partitioning schemes that may not compute BCPs.

Main Results:

• Successfully achieved origin-independence for local fragment dipole moments.
• Demonstrated applicability to systems with large interfragment distances and where BCPs are absent.
• The approach is valid for both covalently and noncovalently bound systems.

Conclusions:

• The new method offers a reliable way to calculate local electric dipole moments for molecular fragments.
• It overcomes limitations of existing origin-dependent methods and BCP-based approaches.
• This advancement aids in the accurate study of nanoelectronics, spectroscopy, and solvent effects.