Coupled-cluster chemical

Hess, B.A. and Kaldor, U. (2000) Relativistic all-electron coupled-cluster calculations on Au2 in the framework of the Douglas—Kroll transformation. Journal of Chemical Physics, 112, 1809-1813. 

Wesendrup, R., Laerdahl, J.K and Schwerdtfeger, P. (1999) Relativistic Effects in Gold Chemistry. VI. Coupled Cluster Calculations for the Isoelectronic Series AuPt , Au2 and AuHg. Joumul of Chemical Physics, 110, 9457-9462. 

Fossgaard, O., Gropen, O., Eliav, E. and Saue, T. (2003) Bonding in the homologous series CsAu, CsAg, and CsCu studied at the 4-component density functional theory and coupled cluster levels. Journal of Chemical Physics, 119, 9355-9363. 

Schwerdtfeger, P., Bast, R., Gerry, M.C.L., Jacob, C.R., Jansen, M., Kelld, V., Mudring, A.V., Sadlej, A.J., Saue, T, Sdhnel, T. and Wagner, F.E. (2005) The quadrupole moment of the 3 /2 nuclear groimd state of Au from electric field gradient relativistic coupled cluster and density functional theory of small molecules and the solid slide. Journal of Chemical Physics, 122,124317-1-124317-9. 

Seth, M., Cooke, F., Pehssier, M., Heully J.-L. and Schwerdtfeger, P. (1998) The Chemistry of the Superheavy Elements II. The Stability of High Oxidation States in Group 11 Elements. Relativistic Coupled Cluster Calculations for the Fluorides of Cu, Ag, Au and Element 111. Journal of Chemical Physics, 109, 3935—3943. 

Belpassi, L., Infante, I., Tarantelli, E. and Visscher, L. (2008) The Chemical Bond between Au(I) and the Noble Gases. Comparative Study of NgAuF and NgAu (Ng) Ar, Kr, Xe) by Density Functional and Coupled Cluster Methods. Journal of the... 

Fleig T, Knecht S, Hattig C (2007) Quantum-chemical investigation of the structures and electronic spectra of the nucleic acid bases at the coupled cluster CC2 level. J Phys Chem A 111 5482-5491... 

The allyl-resonance stabilized E- and Z-pent-l,3-dienyl-2-cations (22 and 23) are the smallest member of vinyl cations observed as persistent species in superacid solution 49 These are difficult to generate experimentally50 but structures with only five heavy atoms are suitable candidates for coupled cluster model calculations. A challenging task of quantum chemistry was to assign the 13C NMR spectrum of the mixture of isomers (Fig. 3), which exhibits pairs of signals of 22 and 23 which differ only by a few ppm, to the chemical shifts for the specific carbon atoms of the E- and Z-isomers, respectively. 

The GIAO-MP2/TZP calculated 13C NMR chemical shifts of the cyclopropylidene substituted dienyl cation 27 show for almost all carbon positions larger deviations from the experimental shifts than the other cations 22-26. The GIAO-MP2/TZP method overestimates the influence of cr-delocalization of the positive charge into the cyclopropane subunit on the chemical shifts. Electron correlation corrections for cyclopropylidenemethyl cations such as 27 and 28 are too large to be adequately described by the GIAO-MP2 perturbation theory method and higher hierarchies of approximations such as coupled cluster models are required to rectify the problem. 

Recently, quantum chemical computational techniques, such as density functional theory (DFT), have been used to study the electrode interface. Other methods ab initio methods based on Hartree-Fock (HF) theory,65 such as Mollcr-PIcsset perturbation theory,66,67 have also been used. However, DFT is much more computationally efficient than HF methods and sufficiently accurate for many applications. Use of highly accurate configuration interaction (Cl) and coupled cluster (CC) methods is prohibited by their immense computational requirements.68 Advances in computing capabilities and the availability of commercial software packages have resulted in widespread application of DFT to catalysis. 

From these expressions, it is evident that the steep increase of the computational cost with X (the basis-set hierarchy) and m (the coupled-cluster hierarchy) severely restricts the levels of theory that can be routinely used for large systems or even explored for small systems. Nevertheless, we shall see that, with current computers, it is possible to arrange the calculations in such a manner that chemical accuracy (of the order of 1 kcal/mol 4 kJ/mol) can be achieved - at least for molecules containing not more than ten first-row atoms. 

The field of quantum chemistry has seen tremendous development over the last thirty years. Thanks to high-accuracy models such as coupled-cluster theory and standardized, widely available program packages such as Gaussian 98, what was once merely an esoteric tool of a few specialists has evolved into an indispensable source of knowledge for both the prediction and the interpretation of chemical phenomena. With the development of reduced scaling algorithms for coupled cluster... 

J. Paldus and X. Li, A Critical Assessment of Coupled Cluster Method in Quantum Chemistry, Volume 110 of Advances in Chemical Physics, Wiley, Hoboken, NJ, 1999, p. 1. 

The most practical and useful HoMQC methods are the 2Q- and 3Q-HoMQC techniques. In combination they offer extensive information about connectivity and topology through chemical bonds for most biomolecules. 2Q-HoMQC spectra are perhaps most important because they reveal the smallest coupled clusters in spin systems where at least two spins are connected with reasonable coupling constants. In addition a great variety of other connectivities will usually show up. Sensitivity of 2Q spectra is also... 

M. Urban, J. Noga, S. J. Cole, and R. J. Bartlett, J. Chem. Phys. 83, 4041 (1985). T. J. Lee, G. E. Scuseria, Achieving Chemical Accuracy with Coupled-Cluster Theory. In S. R. Langhoff (Ed.) Quantum Mechanical Electronic Structure Calculations with Chemical Accuracy (Kluwer, Dordrecht, 1995), pp. 47-108. 

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