Distributed Multipole Analysis:  Stability for Large Basis Sets.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Molecular modeling

Background:

• Distributed multipole analysis (DMA) describes molecular charge distributions using atomic multipole moments.
• Standard DMA methods exhibit instability and unpredictable changes in calculated moments with basis set variations.
• These variations occur despite minimal changes in the overall electrostatic potential.

Purpose of the Study:

• To develop a more stable and reliable method for distributed multipole analysis.
• To address the basis set sensitivity issue in calculating molecular multipole moments.
• To achieve rapid convergence of multipole moments with increasing basis set size.

Main Methods:

• A revised procedure for DMA is proposed.
• Grid-based quadrature is employed to partition charge density contributions from diffuse basis functions.
• The stability and convergence of the new method are tested against basis set changes.

Main Results:

• The revised DMA procedure demonstrates significant stability with respect to basis set changes.
• Calculated multipole moments show rapid and predictable convergence as the basis set size increases.
• The new method overcomes the unpredictability of the original DMA approach.

Conclusions:

• The proposed grid-based quadrature method offers a robust and stable alternative for distributed multipole analysis.
• This approach ensures reliable calculation of molecular multipole moments, crucial for accurate charge distribution analysis.
• The rapid convergence facilitates efficient and dependable computational chemistry workflows.