Static versus dynamically polarizable environments within the many-body GW formalism.

Area of Science:

• Computational Chemistry
• Materials Science
• Quantum Mechanics

Background:

• Polarizable models for optoelectronic processes often assume an instantaneous electronic dielectric response (adiabatic limit).
• This assumption simplifies calculations but may limit accuracy for embedded subsystems.
• The accuracy of the adiabatic limit needs rigorous assessment against fully dynamic dielectric responses.

Purpose of the Study:

• To evaluate the accuracy of the adiabatic approximation for the electronic dielectric response in embedded subsystems.
• To introduce methods for correctly incorporating the static limit of environmental susceptibility.
• To quantify errors introduced by the adiabatic assumption in optoelectronic property calculations.

Main Methods:

• Utilized a newly developed embedded GW formalism with a fully ab initio description of the environment.
• Introduced Coulomb-hole and screened-exchange contributions to the reaction field for static limit calculations.
• Applied the formalism to a C60 molecule on a C60 crystal surface and a water molecule in a metallic nanotube.

Main Results:

• The adiabatic approximation, when properly handled, results in errors below 10% for polarization energies of frontier levels and energy gaps in the C60/C60 crystal system.
• For a water molecule in a metallic nanotube, a challenging case, the error on gap polarization energy remains below 10%.
• However, errors on frontier orbital polarization energies can reach several tenths of an electronvolt in the water/nanotube system.

Conclusions:

• The adiabatic approximation is a reliable approach for studying optoelectronic processes in many embedded systems, particularly when considering energy gaps.
• The study provides a robust framework for assessing and improving the accuracy of polarizable models for condensed-phase and nanoscale systems.
• Careful consideration of specific orbital energies is necessary in systems with significant electronic response dynamics.