Operator Formalism for Noncollinear Functionals in the Multicollinear Approach.

Area of Science:

• Condensed matter physics
• Quantum chemistry
• Materials science

Background:

• Accurate modeling of spin-orbit coupling and noncollinear magnetism necessitates noncollinear density functionals within the generalized Kohn-Sham framework.
• Developing and implementing these noncollinear functionals presents significant challenges.

Purpose of the Study:

• To derive the operator formalism for the multicollinear approach, extending collinear functionals to noncollinear ones.
• To implement these novel equations in the NCXC noncollinear functional ensemble for enhanced DFT software compatibility.
• To validate the accuracy of the multicollinear approach in practical periodic systems.

Main Methods:

• Derivation of the operator formalism for the multicollinear approach.
• Implementation of the derived equations into the NCXC functional ensemble.
• Application and validation in periodic systems, including spin spirals, topological insulators, and semiconductors.

Main Results:

• Successful derivation and implementation of the operator formalism for the multicollinear approach.
• The NCXC ensemble demonstrates improved compatibility with DFT software.
• Validation confirms accuracy in modeling noncollinear magnetism, band structures, and band gaps.

Conclusions:

• The operator formalism of the multicollinear approach provides a robust method for noncollinear density functional theory.
• The NCXC ensemble facilitates accurate calculations of electronic and magnetic properties in diverse materials.
• This work advances the capability of DFT for studying complex magnetic and electronic phenomena.