Jump to main content
Jump to site search

Issue 21, 2012
Previous Article Next Article

Hybrid one-electron/many-electron methods for ionized states of molecular clusters

Author affiliations

Abstract

To describe singly-ionized states of molecular clusters we devised an effective Hamiltonian approach that combines (1) accurate monomer ionization potentials from many-electron wave functions with (2) polarization shifts and (3) effective monomer couplings obtained from a simple one-electron approach (the superposition-of-fragment-states (SFS) method [Valeev et al., J. Am. Chem. Soc., 2006, 128, 9882]). The accuracy of the intermolecular coupling parameters evaluated with SFS Hartree–Fock (HF) and Density-Functional-Theory (DFT) variants was evaluated for several weakly-bound dimers and compared against the state-of-the-art equation-of-motion ionization-potential coupled-cluster singles and doubles (EOM-IP-CCSD) data of Krylov and co-workers. The SFS–HF method produces coupling integrals accurate to a few percent, whereas SFS–DFT predictions are substantially worse. A hybrid approach combining SFS–HF couplings and shifts with EOM-IP-CCSD ionization potentials of monomers (denoted as SFS-EOM-IP-CCSD) was applied to ionized states of two conformers of a benzene dimer and ten representative DNA base pairs. The 16 considered SFS-EOM-IP-CCSD ionization potentials of the benzene dimer differed from the reference EOM-IP-CCSD IPs of Krylov and co-workers [Pieniazek et al., J. Chem. Phys. 2007, 127, 044317; Bravaya et al., Phys. Chem. Chem. Phys. 2010, 12, 2261] by less than 0.1 eV on average, and at most by 0.2 eV. For the DNA base pairs the mean absolute (median) deviation of the SFS-EOM-IP-CCSD IPs was 0.27 (0.23) eV; several deviations for non-Koopmans states were as large as 0.9 eV. The SFS-EOM-IP-CCSD method can be readily applied to large molecular clusters with computational effort scaling cubically with the size of the cluster.

Graphical abstract: Hybrid one-electron/many-electron methods for ionized states of molecular clusters

Back to tab navigation
Please wait while Download options loads

Publication details

The article was received on 23 Jan 2012, accepted on 17 Apr 2012 and first published on 18 Apr 2012


Article type: Paper
DOI: 10.1039/C2CP40222J
Citation: Phys. Chem. Chem. Phys., 2012,14, 7863-7871
  •   Request permissions

    Hybrid one-electron/many-electron methods for ionized states of molecular clusters

    J. Zhang and E. F. Valeev, Phys. Chem. Chem. Phys., 2012, 14, 7863
    DOI: 10.1039/C2CP40222J

Search articles by author