Accurate and systematically improvable density functional theory embedding for correlated wavefunctions

Jason D. Goodpaster*, Taylor A. Barnes, Frederick R. Manby, Thomas F. Miller

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

99 Citations (Scopus)
257 Downloads (Pure)

Abstract

We analyze the sources of error in quantum embedding calculations in which an active subsystem is treated using wavefunction methods, and the remainder using density functional theory. We show that the embedding potential felt by the electrons in the active subsystem makes only a small contribution to the error of the method, whereas the error in the nonadditive exchange-correlation energy dominates. We test an MP2 correction for this term and demonstrate that the corrected embedding scheme accurately reproduces wavefunction calculations for a series of chemical reactions. Our projector-based embedding method uses localized occupied orbitals to partition the system; as with other local correlation methods, abrupt changes in the character of the localized orbitals along a reaction coordinate can lead to discontinuities in the embedded energy, but we show that these discontinuities are small and can be systematically reduced by increasing the size of the active region. Convergence of reaction energies with respect to the size of the active subsystem is shown to be rapid for all cases where the density functional treatment is able to capture the polarization of the environment, even in conjugated systems, and even when the partition cuts across a double bond. (C) 2014 AIP Publishing LLC.

Original languageEnglish
Article number18A507
Number of pages9
JournalJournal of Chemical Physics
Volume140
Issue number18
Early online date10 Feb 2014
DOIs
Publication statusPublished - 14 May 2014

Keywords

  • ELECTRON CORRELATION METHODS
  • COUPLED-CLUSTER THEORY
  • TRIPLES CORRECTION T
  • GAUSSIAN-BASIS SETS
  • AB-INITIO
  • MOLECULAR CALCULATIONS
  • CORRELATION-ENERGY
  • LOCAL TREATMENT
  • PART I
  • SYSTEMS

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