Subspace methods for the simulation of molecular response properties on a quantum computer

Peter Reinholdt, Erik Rosendahl Kjellgren*, Juliane Holst Fuglsbjerg, Karl Michael Ziems, Sonia Coriani, Stephan P. A. Sauer, Jacob Kongsted

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

We explore Davidson methods for obtaining excitation energies and other linear response properties within quantum self-consistent linear response (q-sc-LR) theory. Davidson-type methods allow for obtaining only a few selected excitation energies without explicitly constructing the electronic Hessian since they only require the ability to perform Hessian-vector multiplications. We apply the Davidson method to calculate the excitation energies of hydrogen chains (up to H10) and analyze aspects of statistical noise for computing excitation energies on quantum simulators. Additionally, we apply Davidson methods for computing linear response properties such as static polarizabilities for H2, LiH, H2O, OH−, and NH3, and show that unitary coupled cluster outperforms classical projected coupled cluster for molecular systems with strong correlation. Finally, we formulate the Davidson method for damped (complex) linear response, with application to the nitrogen K-edge X-ray absorption of ammonia, and the C6 coefficients of H2, LiH, H2O, OH−, and NH3.
Original languageEnglish
JournalJournal of Chemical Theory and Computation
Volume20
Issue number9
Pages (from-to)3729-3740
Number of pages12
ISSN1549-9618
DOIs
Publication statusPublished - 1 May 2024

Keywords

  • Faculty of Science
  • Quantum Computing
  • linear response theory
  • excitation energies
  • polarizability

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