A general coupled cluster study of the N2 molecule

Krogh, Jesper Wisborg; Olsen, Jeppe

doi:10.1016/s0009-2614(01)00853-3

Cited by 74 publications

(48 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To further increase the reliability of the dynamic electron correlation treatment, we are also extending LUCIAREL by merging it with a new multireference coupled cluster ͑MRCC͒ method 37,38 opening for Kramersrestricted MRCC treatments. Based on KR-MCSCF wave functions, this method will allow for coupled cluster calculations on heavy-element molecules with an arbitrary number of open shells.…”

Section: Discussionmentioning

confidence: 99%

The generalized active space concept for the relativistic treatment of electron correlation. III. Large-scale configuration interaction and multiconfiguration self-consistent-field four-component methods with application to UO2

Fleig

Jensen

Olsen

et al. 2006

The Journal of Chemical Physics

Self Cite

121

109

View full text Add to dashboard Cite

We present an implementation for large-scale relativistic electronic structure calculations including spin-dependent contributions and electron correlation in a fully variational procedure. The modular implementation of the double group configuration interaction ͑CI͒ program into a multiconfiguration self-consistent-field ͑MCSCF͒ code allows for the treatment of large CI expansions in both the spinor optimization step and the post-MCSCF dynamic electron correlation step. As an illustration of the potential of the new code, we calculate the spectroscopic properties of the UO 2 molecule where we study the ground state and a few excited states in vertical and adiabatic calculations.

show abstract

Section: Discussionmentioning

confidence: 99%

The generalized active space concept for the relativistic treatment of electron correlation. III. Large-scale configuration interaction and multiconfiguration self-consistent-field four-component methods with application to UO2

Fleig

Jensen

Olsen

et al. 2006

The Journal of Chemical Physics

Self Cite

121

109

View full text Add to dashboard Cite

show abstract

“…Weaknesses are related to low levels of excitations employed in situations where the single-configuration reference is clearly poor, for instance dissociating or quasi-degenerated situations or systems like ozone, C 2 , N 2 , the NO dimer and others. [10,11,[32][33][34] In those cases, triple or higher excitations have to be included in the cluster expansion. In a recent benchmark study on excitation energies [35] it was shown that CCSD or CC2 is less accurate than complete active space perturbation theory of the second order (or CASPT2, see below)-in the ionization-potential-electron-affinity (IPEA) formulation [36] -for systems with closed-shell ground states.…”

Section: Propagator Approachesmentioning

confidence: 99%

Progress and Challenges in the Calculation of Electronic Excited States

2011

View full text Add to dashboard Cite

A detailed understanding of the properties of electronic excited states and the reaction mechanisms that molecules undergo after light irradiation is a fundamental ingredient for following light-driven natural processes and for designing novel photonic materials. The aim of this review is to present an overview of the ab initio quantum chemical and time-dependent density functional theory methods that can be used to model spectroscopy and photochemistry in molecular systems. The applicability and limitations of the different methods as well as the main frontiers are discussed. To illustrate the progress achieved by excited-state chemistry in the recent years as well as the main challenges facing computational chemistry, three main applications that reflect the authors' experience are addressed: the UV/Vis spectroscopy of organic molecules, the assignment of absorption and emission bands of organometallic complexes, and finally, the obtainment of non-adiabatic photoinduced pathways mediated by conical intersections. In the latter case, special emphasis is put on the photochemistry of DNA. These applications show that the description of electronically excited states is a rewarding but challenging area of research.

show abstract

“…7 These calculations thus go beyond previous full configuration interaction ͑FCI͒ studies, which used the frozen-core (10 e) approximation. 1,6 Allelectron FCI calculations ͓which retain all elements of the configuration interaction ͑CI͒ vector͔ for this system remain currently out of reach ͑the D 2h space contains roughly 1.8 ϫ10 11 determinants͒. While the DMRG and CC theories should be seen as providing a hierarchy of approximations to the FCI result, our calculations have been carried out to a very high level (M ϭ4000 for DMRG, and up to hextuple excitations for CC theory͒, yielding near-FCI quality numerical results.…”

Section: Introductionmentioning

confidence: 99%

State-of-the-art density matrix renormalization group and coupled cluster theory studies of the nitrogen binding curve

Chan

Kállay

Gauß

2004

The Journal of Chemical Physics

192

231

View full text Add to dashboard Cite

We study the nitrogen binding curve with the density matrix renormalization group ͑DMRG͒ and single-reference and multireference coupled cluster ͑CC͒ theory. Our DMRG calculations use up to 4000 states and our single-reference CC calculations include up to full connected hextuple excitations. Using the DMRG, we compute an all-electron benchmark nitrogen binding curve, at the polarized, valence double-zeta level ͑28 basis functions͒, with an estimated accuracy of 0.03 mE h . We also assess the performance of more approximate DMRG and CC theories across the nitrogen curve. We provide an analysis of the relative strengths and merits of the DMRG and CC theory under different correlation conditions.

show abstract

A general coupled cluster study of the N2 molecule

Cited by 74 publications

References 21 publications

The generalized active space concept for the relativistic treatment of electron correlation. III. Large-scale configuration interaction and multiconfiguration self-consistent-field four-component methods with application to UO2

The generalized active space concept for the relativistic treatment of electron correlation. III. Large-scale configuration interaction and multiconfiguration self-consistent-field four-component methods with application to UO2

Progress and Challenges in the Calculation of Electronic Excited States

State-of-the-art density matrix renormalization group and coupled cluster theory studies of the nitrogen binding curve

Contact Info

Product

Resources

About