Quantum control of coherent π-electron ring currents in polycyclic aromatic hydrocarbons

Area of Science:

• Quantum chemistry
• Molecular physics
• Organic chemistry

Background:

• Polycyclic aromatic hydrocarbons (PAHs) exhibit complex coherent π electron ring currents.
• Controlling these currents is crucial for understanding and manipulating molecular properties.

Purpose of the Study:

• To develop and demonstrate a quantum optimal control (QOC) method for precisely generating specific π electron ring current patterns in PAHs.
• To explore different types of ring currents, including localized, perimeter, and middle ring currents.

Main Methods:

• Utilized a Lagrange multiplier method to determine the optimal target wavefunction for desired ring current generation.
• Integrated the target function into standard QOC theory.
• Performed time-dependent simulations of excited electronic states and laser pulse electric fields.

Main Results:

• Successfully demonstrated the QOC procedure on naphthalene and anthracene.
• Clarified the mechanisms of ring current generation through analysis of temporal evolutions.
• Reproduced QOC results using time-dependent simulations of induced perimeter and middle ring currents.

Conclusions:

• QOC is an effective method for controlling coherent π electron ring currents in PAHs.
• The study provides a foundational understanding of generating specific current pathways in molecules like naphthalene and anthracene.