Propagators in Quantum Chemistry

Linderberg, Jan; Öhrn, Yngve

doi:10.1002/0471721549

Cited by 349 publications

(389 citation statements)

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“…22 In this case, outer valence orbital binding energies were calculated with the partial third-order quasiparticle theory of the electron propagator ͑P3͒. 23 In Green's function schemes, 24,25 orbital energies and spectral intensities are available as pole position and pole strengths, respectively, of the spectral representation of the Green's function. [23][24][25][26] The second approach was coupled cluster with single and double excitations, and perturbative treatment of triples [27][28][29][30] ͓CCSD͑T͔͒, and it was restricted to total energy difference calculations of the neutral and ionic systems to predict the first vertical ionization potentials ͑IPs͒ and electron affinities ͑EAs͒.…”

Section: A Quantum Mechanics Calculationsmentioning

confidence: 99%

Electronic properties of liquid ammonia: A sequential molecular dynamics/quantum mechanics approach

Almeida

Coutinho

Cabral

et al. 2008

The Journal of Chemical Physics

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Electronic structures of c-plane and a-plane AlN/ZnO heterointerfaces determined by synchrotron radiation photoemission spectroscopy Appl. Phys. Lett. 97, 252111 (2010) Theoretical predictions of trends in spectroscopic properties of gold containing dimers of the 6p and 7p elements and their adsorption on gold J. Chem. Phys. 133, 104304 (2010) Additional information on J. Chem. Phys. The electronic properties of liquid ammonia are investigated by a sequential molecular dynamics/ quantum mechanics approach. Quantum mechanics calculations for the liquid phase are based on a reparametrized hybrid exchange-correlation functional that reproduces the electronic properties of ammonia clusters ͓͑NH 3 ͒ n ; n =1-5͔. For these small clusters, electron binding energies based on Green's function or electron propagator theory, coupled cluster with single, double, and perturbative triple excitations, and density functional theory ͑DFT͒ are compared. Reparametrized DFT results for the dipole moment, electron binding energies, and electronic density of states of liquid ammonia are reported. The calculated average dipole moment of liquid ammonia ͑2.05± 0.09 D͒ corresponds to an increase of 27% compared to the gas phase value and it is 0.23 D above a prediction based on a polarizable model of liquid ammonia ͓Deng et al., J. Chem. Phys. 100, 7590 ͑1994͔͒. Our estimate for the ionization potential of liquid ammonia is 9.74± 0.73 eV, which is approximately 1.0 eV below the gas phase value for the isolated molecule. The theoretical vertical electron affinity of liquid ammonia is predicted as 0.16± 0.22 eV, in good agreement with the experimental result for the location of the bottom of the conduction band ͑−V 0 = 0.2 eV͒. Vertical ionization potentials and electron affinities correlate with the total dipole moment of ammonia aggregates.

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Section: A Quantum Mechanics Calculationsmentioning

confidence: 99%

Electronic properties of liquid ammonia: A sequential molecular dynamics/quantum mechanics approach

Almeida

Coutinho

Cabral

et al. 2008

The Journal of Chemical Physics

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“…One straightforward way to characterize this gating process would be to use an on-site Coulomb repulsion picture, which is the Hubbard limit of the Pariser-Parr-Pople model. 29 For such a situation, the molecular Hamiltonian can then be approximated (at the Hartree-Fock level) by…”

Section: Comparative Modifications: Covalency and Coulomb Gatingmentioning

confidence: 99%

Molecular Wire Junctions: Tuning the Conductance

et al. 2002

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Junctions consisting of two electrodes and a single molecule acting as a wire can be investigated by scanning probe conductance measurements. The conductance for low temperature, short wire structures can be characterized by the elastic scattering of the electrons, as described by general Landauer formulas. Tuning the bridge energy levels either by field effect transistor (FET)-like behavior (charging) or by chemical bond formation can raise or lower the conductance by moving the poles of the molecular Green's function. For small molecular structures with particular HOMO/LUMO characteristics, functionalization might be a more effective means than Coulomb charging by external gates.

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“…1,[4][5][6][7][8][9][10] Within the CI approaches, highly correlated configuration interaction 11 ͑HCCI͒ methods, viz., CI going well beyond the singles and doubles treatment, constitutes a practical alternative to using a full Hamiltonian representation, particularly after the developments in the companion paper 12 to be referred to as I. One possibility is to select a priori a subspace S having invariant properties with respect to separate unitary transformations of the occupied orbitals and of distinct sets of correlation orbitals grouped in a well-defined manner, 11 giving rise to multireference CI ͑MRCI͒, [13][14][15][16][17][18] complete active space ͑CAS͒ CI, 19 restricted active space ͑RAS͒ CI, 20 and so on.…”

Section: Introductionmentioning

confidence: 99%

Select-divide-and-conquer method for large-scale configuration interaction

Bunge

Carbó‐Dorca

2006

The Journal of Chemical Physics

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A select-divide-and-conquer variational method to approximate configuration interaction ͑CI͒ is presented. Given an orthonormal set made up of occupied orbitals ͑Hartree-Fock or similar͒ and suitable correlation orbitals ͑natural or localized orbitals͒, a large N-electron target space S is split into subspaces S 0 , S 1 , S 2 , ... ,S R . S 0 , of dimension d 0 , contains all configurations K with attributes ͑energy contributions, etc.͒ above thresholds T 0 ϵ͕T 0 egy , T 0 etc.͖; the CI coefficients in S 0 remain always free to vary. S 1 accommodates Ks with attributes above T 1 ഛ T 0 . An eigenproblem of dimension d 0 + d 1 for S 0 + S 1 is solved first, after which the last d 1 rows and columns are contracted into a single row and column, thus freezing the last d 1 CI coefficients hereinafter. The process is repeated with successive S j ͑j ജ 2͒ chosen so that corresponding CI matrices fit random access memory ͑RAM͒. Davidson's eigensolver is used R times. The final energy eigenvalue ͑lowest or excited one͒ is always above the corresponding exact eigenvalue in S. Threshold values ͕T j ; j =0,1,2, ... ,R͖ regulate accuracy; for large-dimensional S, high accuracy requires S 0 + S 1 to be solved outside RAM. From there on, however, usually a few Davidson iterations in RAM are needed for each step, so that Hamiltonian matrix-element evaluation becomes rate determining. One hartree accuracy is achieved for an eigenproblem of order 24ϫ 10 6 , involving 1.2ϫ 10 12 nonzero matrix elements, and 8.4ϫ 10 9 Slater determinants.

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Propagators in Quantum Chemistry

Cited by 349 publications

References 0 publications

Electronic properties of liquid ammonia: A sequential molecular dynamics/quantum mechanics approach

Electronic properties of liquid ammonia: A sequential molecular dynamics/quantum mechanics approach

Molecular Wire Junctions: Tuning the Conductance

Select-divide-and-conquer method for large-scale configuration interaction

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