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Authors: J. Friedrich, M. Hanrath, and M. Dolg
The field of local correlation methods is a recent branch in quantnum chemistry, with a varity of different local coupled cluster approaches [1-6]. The Incremental Scheme of Stoll and Nesbet [7,8] provides an alternative way to obtain the coupled cluster correlation energy. We present a general fully automated implementation of the incremental scheme for molecules and embedded clusters in the framework of the coupled cluster singles and doubles theory. The code can be applied to arbitrary order of the incremental expansion and is parallelized in a master/slave structure. We found that the error in the total correlation energy is small with respect to the canonical CCSD calculation, if the incremental series is truncated at third or fourth order. The potential accuracy of the incremental scheme is demonstrated explicitly for transition metal complexes [9], intermolecular systems [10] and cluster compounds [11]. Furthermore we present a systematic screening procedure for small contributions in the incremental expansion of the correlation energy. The performance of the proposed truncation scheme is checked for the calculation of the guanine-cytosine base pair. The computational cost for the incremental expansion can be considerably reduced without significant loss of accuracy. Typically the errors of the systems investigated here amount to less than 5 %, 1 % and 0.1 % for second, third and fourth order expansions, respectively. [1] C. Hampel, and H-J. Werner, J. Chem. Phys. 104, 6286 (1996). [2] M. Schütz, J. Chem. Phys. 113, 9986 (2000). [3] N. Flocke, and R. J. Bartlett, J. Chem. Phys. 121, 10935 (2004). [4] J. E. Subotnik, and M. Head-Gordon, J. Chem. Phys. 123, 74116 (2005). [5] A. Auer, and M. Nooijen, J. Chem. Phys. 125, 24104 (2006). [6] O. Christiansen, P. Manninen, P. Jørgenson, and J. Olsen, J. Chem. Phys. 124, 84103 (2006). [7] R. K. Nesbet, Adv. Chem. Phys. 14, 1 (1969). [8] H. Stoll, J. Chem. Phys. 97, 6700 (1992). [9] J. Friedrich, M. Hanrath, and M. Dolg, J. Chem. Phys. 126, 154110 (2007). [10] J. Friedrich, M. Hanrath, and M. Dolg, J. Phys. Chem. A (revised). [11] J. Friedrich, M. Hanrath, and M. Dolg, Chem. Phys. (submitted)). |
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