Optical Absorption Spectra Calculated from a First-Principles Wave Function Theory for Solids: Transcorrelated Method...

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Wave Function Theory

Background:

• Conventional Configuration Interaction Singles (CIS) with Hartree-Fock (HF) struggles with electron correlation.
• This limitation leads to inaccuracies in excited-state calculations, like overestimating band gaps and exciton binding energies in materials.

Purpose of the Study:

• To develop a novel ab initio method for improved excited-state calculations.
• To accurately capture electron correlation effects in molecular and solid-state systems.
• To enhance the prediction of optical absorption spectra and excitonic effects.

Main Methods:

• Combining the transcorrelated (TC) method with Configuration Interaction Singles (CIS).
• The TC method incorporates electron correlation via a similarity transformation of the Hamiltonian using a Jastrow factor.
• Applying the combined TC-CIS method to calculate optical absorption spectra.

Main Results:

• The developed TC-CIS method provides more accurate optical absorption spectra compared to conventional HF-CIS.
• Accurate reproduction of spectra for solid LiF and GaAs demonstrates the method's efficacy.
• The method effectively describes the excitonic effect, a key aspect of excited states.

Conclusions:

• The transcorrelated method combined with CIS offers a significant advancement for excited-state calculations.
• This approach overcomes limitations of traditional methods by including electron correlation.
• The TC-CIS method shows promise for accurate material property predictions, particularly concerning optical and excitonic behavior.