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Updated: Dec 11, 2025
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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
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N5-Scaling Excited-State-Specific Perturbation Theory
Rachel Clune1, Jacqueline A R Shea1, Eric Neuscamman1,2
1Department of Chemistry, University of California, Berkeley, California 94720, United States.
Journal of Chemical Theory and Computation
|August 21, 2020
Summary
This study reduces the computational cost of excited-state mean field theory corrections from seventh to fifth order. The optimized method maintains accuracy comparable to established computational chemistry techniques.
Area of Science:
- Quantum Chemistry
- Computational Physics
- Theoretical Chemistry
Background:
- Excited-state calculations are crucial for understanding molecular properties.
- Perturbative corrections to mean field theory offer a balance of accuracy and cost.
- Previous methods for excited-state mean field theory corrections had high computational scaling.
Purpose of the Study:
- To reduce the computational cost of a specific perturbative correction to excited-state mean field theory.
- To analyze the scaling and accuracy of the modified method.
- To enable more efficient excited-state electronic structure calculations.
Main Methods:
- Utilizing a basis set similar to natural transition orbitals.
- Employing a modified zeroth-order Hamiltonian.
- Implementing automatic code generation for cost scaling analysis.
- Solving linear equations using Krylov-subspace methods.
Main Results:
- Reduced the computational cost from seventh to fifth order in system size.
- Achieved an (occupied)2(virtual)3 asymptotic scaling.
- The bottleneck remains an iterative process for the first-order wave function.
- Modifications showed minimal impact on the method's accuracy.
Conclusions:
- The modified approach significantly enhances the efficiency of excited-state mean field theory corrections.
- The method's accuracy remains competitive with high-level methods like singles and doubles equation-of-motion coupled cluster.
- This work paves the way for more accessible and accurate excited-state electronic structure investigations.
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