Ab initio study of stoichiometric gallium phosphide clusters

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Mechanics

Background:

• Gallium phosphide (GaP) is a crucial semiconductor material.
• Understanding the electronic properties of GaP clusters is essential for predicting bulk behavior.
• Static dipole polarizability is a key property influencing material response to electric fields.

Purpose of the Study:

• To investigate the static dipole polarizability of stoichiometric gallium phosphide clusters (Ga(n)P(n), n=2-5).
• To evaluate the performance of various ab initio wave function methods and density functional theory/time dependent density functional theory (DFT/TDDFT) approaches.
• To analyze the influence of different exchange-correlation functionals on polarizability calculations.

Main Methods:

• Ab initio wave function based methods
• Density functional theory/time dependent density functional theory (DFT/TDDFT)
• Various exchange-correlation functionals including Local Density Approximation (LDA), Generalized Gradient Approximation (GGA), and Statistical Average of Orbital Potential (SAOP)

Main Results:

• Polarizability values calculated using SAOP were lower than those from LDA and GGA.
• DFT/TDDFT results using Perdew-Burke-Ernzerhof (PBE) exchange with Lee-Yang-Parr (LYP) correlation, and PBE exchange-correlation functionals showed closest agreement with Møller-Plesset perturbation theory.
• Average static dipole polarizability per atom was found to approach the bulk limit from above as cluster size increased.

Conclusions:

• The choice of exchange-correlation functional significantly impacts the accuracy of DFT/TDDFT polarizability calculations for GaP clusters.
• PBE and PBE/LYP functionals provide reliable results for static dipole polarizability in these systems.
• GaP clusters exhibit size-dependent polarizability that converges to bulk values, offering insights into nanoscale material properties.