A self-contained and portable density functional theory library for use in Ab Initio quantum chemistry programs

Area of Science:

• Computational Chemistry
• Quantum Mechanics
• Materials Science

Background:

• The development of accurate exchange-correlation functionals is a central challenge in density functional theory (DFT).
• Implementing various DFT functionals and their higher-order derivatives poses significant computational difficulties.

Purpose of the Study:

• To introduce a systematic and efficient method for implementing density functional theory (DFT) functionals.
• To facilitate the handling and testing of a large number of DFT approximations and their derivatives.

Main Methods:

• Developed a systematic approach for the clean, independent implementation of numerous DFT functionals.
• Created an extensive suite of automatic test routines for verifying functional and derivative correctness and numerical stability.
• Utilized a program for automatic code generation from analytical formulas using freely available tools.

Main Results:

• The proposed method enables the independent management of a large number of DFT functionals.
• Automatic code generation produces code for evaluating functionals and their first, second, third, and fourth derivatives.
• Accelerated development, implementation, and testing of new DFT functionals and approximations.

Conclusions:

• The systematic implementation method significantly simplifies the practical application of diverse DFT functionals.
• Automated code generation and testing routines enhance the reliability and efficiency of DFT research.
• This approach supports the advancement of density functional theory through easier development and validation of new approximations.