Coupled cluster methods for

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

Coupled Cluster Method for Unsaturated Oxygen-Containing Compounds... 

NONITERATIVE COUPLED-CLUSTER METHODS FOR EXCITED ELECTRONIC STATES... 

Inclusion of connected triple excitations in the equation-of-motion coupled-cluster method for calculating excitation energies was also tested on SiFP230. Excitation energies predicted for the lowest triplet state and the two lowest excited singlet states 1 Si and 2 lAi were within a kcal mol 1 of the predictions of the full Cl calculation when triple excitations were included, but only for the 2 3Ai state was there marked improvement over the inclusion of only single and double excitations. 

Jeziorski B, Monkhorst HJ (1981) Coupled-cluster method for multideterminantal reference states. Phys Rev A 24 1668-1681... 

Our present focus is on density functional theory and coupled cluster methods for describing molecular systems interacting with a structured environment, and we focus on the derivation of linear response properties and compare the expressions that we obtain for the two different electronic structure methods. Based on linear response... 

AN INTRODUCTION TO EQUATION-OF-MOTION AND LINEAR-RESPONSE COUPLED-CLUSTER METHODS FOR ELECTRONICALLY EXCITED STATES OF MOLECULES... 

Watts JD, Bartlett RJ (1995) Economical triple excitation equation-of-motion coupled-cluster methods for excitation energies. Chem Phys Lett 233 81-87. 

Watts JD, Bartlett RJ (1996) Iterative and non-iterative triple excitation corrections in coupled-cluster methods for excited electronic states The EOM-CCSDT-3 and EOM-CCSD(r) methods. Chem Phys Lett 258 581-588. 

Kowalski K, Piecuch P (2000) The active-space equation-of-motion coupled-cluster methods for excited states The EOMCCSDt approach. J Chem Phys 113 8490-8502. 

R. J. Bartlett, C. E. Dykstra, and J. Paldus, in Advanced Theories and Computational Approaches to the Electronic Structure of Molecules, C. E. Dykstra, Ed., D. Reidel, Dordrecht, 1984, pp. 127-159. Coupled-Cluster Methods for Molecular Calculations. 

M. Nooijen and R. J. Bartlett, J. Chem. Phys., 102, 3629 (1995). Equation-of-Motion Coupled-Cluster Method for Electron Attachment. 

Molecular polarizabilities and hyperpolarizabilities are now routinely calculated in many computational packages and reported in publications that are not primarily concerned with these properties. Very often the calculated values are not likely to be of quantitative accuracy when compared with experimental data. One difficulty is that, except in the case of very small molecules, gas phase data is unobtainable and some allowance has to be made for the effect of the molecular environment in a condensed phase. Another is that the accurate determination of the nonlinear response functions requires that electron correlation should be treated accurately and this is not easy to achieve for the molecules that are of greatest interest. Very often the higher-level calculation is confined to zero frequency and the results scaled by using a less complete theory for the frequency dependence. Typically, ab initio studies use coupled-cluster methods for the static values scaled to frequencies where the effects are observable with time-dependent Hartree-Fock theory. Density functional methods require the introduction of specialized functions before they can cope with the hyperpolarizabilities and higher order magnetic effects. 

EOMXCC A New Coupled-Cluster Method for Electronic Excited States... 

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