Communication: Embedded fragment stochastic density functional theory.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Kohn-Sham density functional theory (DFT) is a powerful tool for electronic structure calculations.
• Stochastic DFT offers computational advantages but suffers from slow convergence and charge fluctuations in weakly coupled systems.

Purpose of the Study:

• To develop an improved stochastic DFT method for accurate electronic density calculations.
• To overcome limitations of existing stochastic DFT approaches, specifically slow convergence and spurious charge fluctuations.

Main Methods:

• Embedding electronic densities of small fragments calculated via Kohn-Sham DFT.
• Utilizing stochastic DFT to reconstruct the exact density of the full system.
• Applying the method to a fullerene dimer and water molecule clusters.

Main Results:

• The new method preserves the efficiency and simplicity of stochastic DFT.
• It effectively cures slow convergence issues with weakly coupled subsystems.
• Spurious charge fluctuations are overcome, improving accuracy.

Conclusions:

• The developed method accurately describes the density of states and total energy.
• Achieves high accuracy with a reduced number of stochastic orbitals.
• Offers a robust approach for electronic structure calculations of complex systems.