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Updated: Jul 7, 2025

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
To guess or not to guess excited state amplitudes during optimization and dynamics
D Vale Cofer-Shabica1, Vishikh Athavale1, Joseph E Subotnik1
1Chemistry, University of Pennsylvania, 231S. 34 Street, Cret Wing 141D, Philadelphia, Pennsylvania 19104-6243, USA.
Abstract:
We report robust initial guesses for the amplitudes and z-vectors in a configuration interaction singles or Tamm-Dancoff approximation calculation that consistently reduce the total number of iterations required for an excited state calculation often by over 50%. The end result of these guesses is that the practicing chemist can expect to generate excited state optimized structures with a total wall time reduced by as much as 30% in the future without any approximations-simply by using information gathered at one geometry and applying it to another geometry.
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