Coupled cluster single double triple

Kucharski SA, Bartlett RJ (1991) Recursive intermediate factorization and complete computational linearization of the coupled-cluster single, double, triple, and quadruple excitation equations. Theor Chim Acta 80 387 105. 

S. A. Kucharski and R.. Bartlett, /. Chem. Phys., 97, 4282 (1992). The Coupled-Cluster Single, Double, Triple, and Quadruple Excitation Method. 

In Table 6.3, the values of De for RfCU are compared with those obtained within various approximations using relativistic effective core potentials (RECP) Kramers-restricted Hartree-Fock (KRHF) (Han et al 1999), averaged RECP including second-order M0ller-Plesset perturbation theory (AREP-MP2) for the correlation part (Han et al. 1999), RECP coupled-cluster single double (triple) [CCSD(T)] excitations (Han et al. 1999), and a Dirac-Fock-Breit (DFB) method (Malli and Styszynski 1998). The AREP-MP2 calculation of De gives 20.4 eV, while the RECP-CCSD(T) method with correlation leads to 18.8 eV. Our value of De of 19.5 eV is just between these calculated values. 

B-CC = Brueckner CC CCD = coupled-cluster doubles CCSD = coupled-cluster singles and doubles CCSDT = coupled-cluster singles, doubles, and triples CCSDTQ = coupled-cluster singles, doubles, triples, and quadruples Cl = configuration interaction EOM = equation-on-motion FCI = full-configuration interaction. 

Unlike the CCSD model, the CCSDT and higher models - such as the coupled-cluster singles-doubles-triples-and-quadruples (CCSDTQ) model [8] - are therefore not treated in detail in this chapter. Fortunately, accurate coupled-cluster models have been developed that include the effects of the connected triples in an approximate fashion. We defer the discussion of such approximate CCSDT treatments to Chapter 14. 

Equilibrium Bond Distance and the Harmonic Frequency for N2 from the 2-RDM Method with 2-Positivity (DQG) Conditions Compared with Their Values from Coupled-Cluster Singles-Doubles with Perturbative Triples (CCD(T)), Multireference Second-Order Perturbation Theory (MRPT), Multireference Configuration Interaction with Single-Double Excitations (MRCI), and Full Configuration Interaction (FCI)". 

Kucharski SA, Wloch M, Musial M, Bartlett RJ (2001) Coupled-cluster theory for excited electronic states The full equation-of-motion coupled-cluster single, double, and triple excitation method. J Chem Phys 115 8263-8266. 

M. R. Hoffmann and H. F. Schaefer, Adv. Quantum Chem., 18,207 (1986). A Full Coupled-Cluster Singles, Doubles, and Triples Model for the Description of Electron Correlation. 

A Full Coupled-Cluster Singles, Doubles, and Triples Model for the Description of... 

---