Doubly, triply, and multiply excited states from a constrained optimized effective potential method

Area of Science:

• Quantum Chemistry
• Computational Physics
• Atomic and Molecular Physics

Background:

• Calculating multiply excited states in atoms and molecules is computationally challenging.
• Existing methods like time-dependent density functional theory have limitations in treating these complex states.

Purpose of the Study:

• To develop and apply a novel Constrained Optimized Effective Potential (COEP) approach for practical calculations of multiply excited states.
• To demonstrate the COEP method's capability in handling doubly, triply, and higher excited states in both atoms and molecules.

Main Methods:

• Utilizes time-independent theory for pure excited states.
• Implements an asymptotic projection method for orthogonality constraints.
• Employs a constrained minimization procedure for calculating doubly excited energies, ensuring orthogonality to lower states.

Main Results:

• The COEP methodology successfully treats doubly, triply, and multiply excited states.
• Demonstrates applicability to both atomic and molecular systems.
• Calculations for He atom and H(2) molecule show the method's performance at different approximation levels.

Conclusions:

• The developed COEP approach offers a robust and versatile tool for calculating multiply excited states.
• COEP provides an accurate alternative to existing methods, particularly for complex electronic configurations.