Open-system Kohn-Sham density functional theory.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Condensed matter physics

Background:

• The source-sink potential (SSP) method models electron transport in molecules by applying complex potentials to enforce boundary conditions.
• Previous work extended SSP to the Hückel and Hubbard models.
• Modeling electron transport in finite systems requires methods that can handle open boundary conditions.

Purpose of the Study:

• To generalize the source-sink potential (SSP) method for first-principles electronic structure theory.
• To develop a computational framework for describing open molecular systems that exchange current density with their environment.
• To extend existing quantum chemical methods to incorporate non-Hermitian Hamiltonians for electron transport studies.

Main Methods:

• Development of a generalized density functional theory for complex non-Hermitian Hamiltonians.
• Integration of SSP with Kohn-Sham theory to describe open systems.
• Extension of the Hartree-Fock method to non-Hermitian, SSP-containing Hamiltonians.
• Application of complex-density functional theory (CODFT) and non-Hermitian Hartree-Fock theory.

Main Results:

• A novel generalized density functional theory for complex non-Hermitian Hamiltonians is presented.
• The SSP method is successfully combined with Kohn-Sham theory for open systems.
• The Hartree-Fock method is extended to handle non-Hermitian Hamiltonians with SSP.
• First applications of CODFT and non-Hermitian Hartree-Fock theory to molecular electron transport are demonstrated.

Conclusions:

• The generalized SSP method provides a powerful framework for studying electron transport in molecular systems.
• This work paves the way for accurate first-principles simulations of open quantum systems.
• The developed methods, CODFT and non-Hermitian Hartree-Fock, offer new avenues for investigating electron transport phenomena.