Electrostatic interaction schemes for evaluating the polarizability of silicon clusters

Area of Science:

• Computational chemistry
• Materials science
• Condensed matter physics

Background:

• Predicting the polarizability of silicon clusters is crucial for understanding their electronic properties.
• Existing methods often struggle to accurately capture the size-dependent polarizability variations.

Purpose of the Study:

• To develop and validate an electrostatic interaction scheme for predicting silicon cluster polarizability.
• To investigate the roles of on-site polarization and charge transfer effects on polarizability.

Main Methods:

• Application of electrostatic interaction schemes to silicon clusters (Si(n), n=3-19).
• Inclusion of on-site polarization and charge transfer effects.
• Comparison of results with B3LYP/6-311G(*) and other first-principles calculations.
• Modeling charge transfer as a function of atomic position relative to the cluster's center of mass.

Main Results:

• An atomic polarizability of ~80% of bulk value reproduces the average polarizability pattern but underestimates by ~25%.
• Incorporating charge transfer effects significantly improves agreement for larger clusters.
• Charge transfer effects enhance the prediction of polarizability anisotropy, especially for larger clusters.

Conclusions:

• Electrostatic effects become dominant over quantum effects in larger silicon clusters.
• The proposed electrostatic scheme, with charge transfer, provides a reliable method for predicting silicon cluster polarizability.
• The model successfully captures size-dependent trends and anisotropy in polarizability.