Brillouin-Wigner coupled-cluster

Multireference Brillouin-Wigner Coupled-Cluster Theory. [Pg.75]

So far, we have specified the wave operator H in the BW form (15). If we adopt an exponential ansatz for the wave operator Cl, we can speak about the single-root multireference Brillouin-Wigner coupled-cluster (MR BWCC) theory. The simplest way how to accomplish the idea of an exponential expansion is to exploit the so-called state universal or Hilbert space exponential ansatz of Jeziorski and Monkhorst [23]... [Pg.83]

I. Hubac, Size Extensive Brillouin-Wigner Coupled-Cluster Theory. In A. Tsipis, V. S. Popov, D. R. Herschbach, and J. S. Avery (Eds.) New Methods in Quantum... [Pg.42]

Demel, O. Rittner, J. Carsky, R. Hubac, I. Multireference Brillouin-Wigner coupled cluster singles and doubles study of the singlet-triplet separation in alkylcarbenes, 7. Phys. Chem. A 2004, 70S, 3125-3128. [Pg.362]

Demel, O. Pittner, J. Multireference Brillouin-Wigner coupled cluster method with singles, doubles, and triples efficient implementation and comparison with approximate approaches, 7. Chem. Phys. 2008,128,104108-104111. [Pg.362]

Multireference Brillouin-Wigner Coupled-Cluster Theory (I. Hubac, J. Masik, P. Mach, J. Urban P. Babinec)... [Pg.331]

MULTIREFERENCE BRILLOUIN-WIGNER COUPLED CLUSTER METHOD... [Pg.470]

Hubac and his co-workers222"231 have explored the use of Brillouin-Wigner perturbation theory in solving the coupled cluster equations. For the case of a single reference function, this approach is entirely equivalent to other formulations of the coupled cluster equations. However, for the multireference case, the Brillouin-Wigner coupled cluster theory shows some promise in that it appears to alleviate the intruder state problem. No doubt perturbative analysis will help to gain a deeper understanding of this approach. [Pg.441]

Multireference Brillouin-Wigner coupled clusters method with noniterative perturbative conrtected triples... [Pg.60]

Multireference Brillouin-Wigner coupled cluster (MR-BWCC) theory applied to the H8 model ... [Pg.60]

Multi-reference Brillouin-Wigner coupled-cluster method with a general model space Molecular Physics 103,2239 (2005)... [Pg.61]

Ground states of BeC and MgC A comparative multireference Brillouin-Wigner coupled cluster and configuration interaction study... [Pg.61]

Multireference Brillouin- Wigner coupled cluster singles and doubles study of the singlet-triplet... [Pg.61]

On the ground stales of CaC and ZnC A multireference Brillouin- Wigner coupled cluster study Journal of Chemical Physics 117, 9733 (2002)... [Pg.62]

Size-extensivity correction for the state-spedfic multireference Brillouin-Wigner coupled-cluster theory... [Pg.63]

Comparison of the Biillouin-Wigner coupled cluster theory wth the standard coupled cluster theory. Cancellation of disconnected terms in the Brillouin Wigner coupled cluster theory Czechoslovak Chemical Communications 62, 829 (1997)... [Pg.63]

Size-consistent Brillouin-Wigner Perturbation-Theory with an Exponentially Parametrized Wave-Function- Brillouin Wigner Coupled Cluster Theory The Physical Review A 50, 4558 (1994)... [Pg.64]

In section 6.1 we briefly describe the single reference Brillouin-Wigner coupled cluster expansions. The multireference case is considered in more detail in section 6.2. [Pg.85]

SINGLE REFERENCE BRILLOUIN-WIGNER COUPLED CLUSTER EXPANSIONS... [Pg.85]

The wave operator Cla, defined in equation (34), can be realized in various ways. The Brillouin-Wigner coupled cluster BWCC method is obtained by... [Pg.85]

Like CC, BWCC is fully extensive. Furthermore, the truncated forms of the Brillouin-Wigner coupled cluster expansion involving single and double substitutions usually designated BWCCD corresponding to the approximation (67) and BWCCSD corresponding to the approximation... [Pg.87]

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