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Title: A first principles approach to the electronic properties of liquid and supercritical CO{sub 2}

The electronic absorption spectra of liquid and supercritical CO{sub 2} (scCO{sub 2}) are investigated by coupling a many-body energy decomposition scheme to configurations generated by Born-Oppenheimer molecular dynamics. A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies were calculated with time dependent density functional theory. A red-shift of ∼ 0.2 eV relative to the gas-phase monomer is observed for the first electronic absorption maximum in liquid and scCO{sub 2}. The origin of this shift, which is not very dependent on deviations from the linearity of the CO{sub 2} molecule, is mainly related to polarization effects. However, the geometry changes of the CO{sub 2} monomer induced by thermal effects and intermolecular interactions in condensed phase lead to the appearance of an average monomeric electric dipole moment 〈μ〉 = 0.26 ± 0.04 D that is practically the same at liquid and supercritical conditions. The predicted average quadrupole moment for both liquid and scCO{sub 2} is 〈Θ〉 = − 5.5 D Å, which is increased by ∼ −0.9 D Å relative to its gas-phase value. The importance of investigating the electronic properties for a better understanding of the role played by CO{sub 2} in supercritical solvation is stressed.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ;  [5]
  1. Grupo de Física Matemática da Universidade de Lisboa, Av. Professor Gama Pinto 2, 1649-003 Lisboa (Portugal)
  2. (Portugal)
  3. (Brazil)
  4. Instituto de Física da Universidade Federal da Bahia, Campus Universitário de Ondina, CEP 40210-340 Salvador, Bahia (Brazil)
  5. Instituto de Física da Universidade de São Paulo, CP 66318, 05314-970 São Paulo, SP (Brazil)
Publication Date:
OSTI Identifier:
22415843
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; BORN-OPPENHEIMER APPROXIMATION; CARBON DIOXIDE; DECOMPOSITION; DENSITY FUNCTIONAL METHOD; ELECTRIC DIPOLE MOMENTS; EXCITATION; HAMILTONIANS; LIQUIDS; MANY-BODY PROBLEM; MOLECULAR DYNAMICS METHOD; MOLECULES; MONOMERS; POLARIZATION; QUADRUPOLE MOMENTS; RED SHIFT; SOLVATION; STRESSES; TEMPERATURE DEPENDENCE; TIME DEPENDENCE