Coupled cluster method applications

J. Geersten, M. Rittby, R.J. Bartlett, The equation-of-motion coupled-cluster method Excitation energies of Be and CO, Chem. Phys. Lett. 164 (1989) 57 D.C. Comeau, R.J. Bartlett, The equation-of-motion coupled-cluster method. Applications to open- and closed-shell reference states, Chem. Phys. Lett. 207 (1993) 414. 

Comeau DC, Bartlett RJ (1993) The equation-of-motion coupled-cluster method Applications to open- and closed-shell reference states. Chem Phys Lett 207 11 1 123. 

M. Rittby and R.. Bartlett,/. Phys. Chem., 92, 3033 (1988). An Open-Shell Spin-Restricted Coupled-Cluster Method Application to Ionization Potentials in N2. 

D. C. Comeau and R. J. Bartlett, Chem. Phys. Lett., 207, 414 (1993). The quation-of-Motion Coupled-Cluster Method Application to Open- and Closed-Shell Reference States. 

Coupled-Cluster Method. Applications to Open- and Closed-Shell References States. 

The coupled-cluster method is well-known by now, and only a brief account of aspects relevant to our applications is given here. 

M. R. Hoffmann and J. A. Simons, A unitary multiconfigurational coupled-cluster method— theory and applications. J. Chem. Phys. 88, 993 (1988). 

Noga, J., Kutzelnigg, W., Klopper, W. CC-R12, a correlation cusp corrected coupled-cluster method with a pilot application to the Be2 potential curve. Chem. Phys. Lett. 1992, 199, 497-504. 

Energy levels of heavy and super-heavy (Z>100) elements are calculated by the relativistic coupled cluster method. The method starts from the four-component solutions of the Dirac-Fock or Dirac-Fock-Breit equations, and correlates them by the coupled-cluster approach. Simultaneous inclusion of relativistic terms in the Hamiltonian (to order o , where a is the fine-structure constant) and correlation effects (all products smd powers of single and double virtual excitations) is achieved. The Fock-space coupled-cluster method yields directly transition energies (ionization potentials, excitation energies, electron affinities). Results are in good agreement (usually better than 0.1 eV) with known experimental values. Properties of superheavy atoms which are not known experimentally can be predicted. Examples include the nature of the ground states of elements 104 md 111. Molecular applications are also presented. 

A. Landan, E. Ehav, and U. Kaldor, Intermediate Hamiltonian Fock-Space Coupled-Cluster Method and Applications. In R. F. Bishop, T. Brandes, K. A. Gernoth, N. R. Walet, and Y. Xian (Eds.) Recent Progress in Many-Body Theories, Advances in Quantum Many-Body Theories, Vol. 6. (World Scientific, Singapore, 2002), pp. 355-364 and references therein. 

Recent developments in computational chemistry have established the exact structure of carbocations by combining computational and experimental results.78,79 Furthermore, accurate 1H and 13C NMR chemical shifts of carbocations and other organic molecules can be calculated with the application of recent coupled cluster methods, such as GIAO-CCSD(T).80... 

E. Eliav, A. Borschevsky, K.R. Shamasundar, S. Pal, U. Kaldor, Intermediate Hamiltonian Hilbert space coupled cluster method Theory and pilot application, Int. J. Quantum Chem. 109 (13) (2009) 2909. 

G.E. Scuseria, The open-shell restricted Hartree-Fock singles and doubles coupled-cluster method including triple excitations CCSD (T) Application to Ca+. Chem. Phys. Lett. 176, 27-35 (1991)... 

Stanton JF, Gauss J (1994) Analytic energy gradients for the equation-of-motion coupled-cluster method Implementation and application to the HCN/HNC system. J Chem Phys 100 4695 1698. 

The CASSCF method itself is not very useful for anything else than systems with few electrons unless an effective method to treat dynamical correlation effects could be developed. The Multi-Reference Cl (MRCI) method was available but was limited due to the steep increase of the size of the Cl expansion as a function of the number of correlated electrons, the basis set, and the number of active orbitals in the reference function. The direct MRCI formulation by P. Siegbahn helped but the limits still prevented applications to larger systems with many valence electrons [20], The method is still used with some success due to recent technological developments [21], Another drawback with the MRCI approach is the lack of size-extensivity, even if methods are available that can approximately correct the energies. Multi-reference coupled-cluster methods are studied but have not yet reached a state where real applications are possible. 

Laidig, W. D. and Bartlett, R. J., A multi-reference coupled-cluster method for molecular applications, Chem. Phys. Lett. 104, 424-430 (1984). 

G. E. Scuseria, Chem. Phys. Lett., 176,27 (1991). The Open-Shell Restricted Hartree-Fock Singles and Doubles Coupled-Cluster Method Including Triple Excitations CCSD(T) Application to C3. 

U. Kaldor, Theor. Chim. Acta, 80, 427 (1991). The Fock Space Coupled Cluster Method Theory and Application. 

L. A. Barnes and R. Lindh, Chem. Phys. Lett., 223, 207 (1994). Symmetry Breaking in O4 An Application of the Brueckner Coupled-Cluster Method. 

RENORMALIZED COUPLED-CLUSTER METHODS THEORETICAL FOUNDATIONS AND APPLICATION TO THE POTENTIAL FUNCTION OF WATER... 

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