Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electronpair bond in Nelectron systems
Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ω{sub α} and oscillator strengths f{sub α} for twoelectron systems if extended to the socalled phase including natural orbital (PINO) theory. The LöwdinShull expression for the energy of twoelectron systems in terms of the natural orbitals and their phases affords in this case an exact phaseincluding natural orbital functional (PILS), which is nonprimitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to Nelectron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the twobody reduced density matrix (2RDM). We now deduce essential features of an Nelectron functional from a wavefunction Ansatz: The extension of the twoelectron LöwdinShull wavefunction to the Nelectron case informs about the phase information. In this paper, applications of this extended LöwdinShull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) twoelectron bondmore »
 Authors:

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 Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands)
 (Korea, Republic of)
 (Saudi Arabia)
 Publication Date:
 OSTI Identifier:
 22253629
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 74 ATOMIC AND MOLECULAR PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CURRENT DENSITY; DENSITY MATRIX; DISSOCIATION; ELECTRON PAIRS; ELECTRONS; EXCITATION; GROUND STATES; OSCILLATOR STRENGTHS; RESPONSE FUNCTIONS; TIME DEPENDENCE; WAVE FUNCTIONS