Combining Pseudopotential and All Electron Density Functional Theory for the Efficient Calculation of Core Spectra...

Area of Science:

• Computational materials science
• Quantum chemistry
• Spectroscopy

Background:

• Density functional theory (DFT) calculations for core spectra like electron energy loss spectra (EELS) typically use computationally intensive all-electron (AE) or efficient projector augmented wave (PAW) methods.
• A computational gap exists between these two primary approaches, limiting flexibility and efficiency.

Purpose of the Study:

• To develop and implement a hybrid computational method that bridges the efficiency of pseudopotential (PSP) methods with the accuracy of all-electron (AE) methods for core spectra calculations.
• To offer a computationally balanced approach for advanced materials analysis.

Main Methods:

• Implementation of a hybrid AE/PSP approach within the multiwavelet madness molecular DFT code.
• Utilizing the multiresolution capabilities of the madness code to handle both AE and PSP treatments of atoms.
• Application to model systems including a small molecule and a carbon nanotube.

Main Results:

• Demonstrated successful integration of AE and PSP treatments for atoms within a single DFT calculation.
• Validated the accuracy and efficiency of the hybrid approach for core-edge calculations.
• Showcased the method's applicability to complex systems like carbon nanotubes.

Conclusions:

• The developed hybrid AE/PSP method offers a computationally efficient and accurate alternative for calculating core spectra (e.g., EELS) using DFT.
• This approach provides a flexible framework for studying core-level phenomena in materials science.
• The multiwavelet madness code is extended to support this novel hybrid computational strategy.