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Bond breaking extended coupled-cluster

Improving the quality of the quasi-degenerate electronic wave functions and the description of bond breaking by the extended coupled-cluster theory... [Pg.167]

The method of moments of coupled-cluster equations (MMCC) is extended to potential energy surfaces involving multiple bond breaking by developing the quasi-variational (QV) and quadratic (Q) variants of the MMCC theory. The QVMMCC and QMMCC methods are related to the extended CC (ECC) theory, in which products involving cluster operators and their deexcitation counterparts mimic the effects of higher-order clusters. The test calculations for N2 show that the QMMCC and ECC methods can provide spectacular improvements in the description of multiple bond breaking by the standard CC approaches. [Pg.37]

Recent years have witnessed a considerable activity towards extending the standard single-reference coupled-cluster (CC) methods (1-9) to potential energy surfaces (PESs) involving bond breaking without invoking a multireference description (see, e.g., refs 9-31). Undoubtedly, it would be very useful if we could routinely calculate large portions of molecular PESs with the ease-... [Pg.37]

See other pages where Bond breaking extended coupled-cluster is mentioned: [Pg.293]    [Pg.230]    [Pg.67]    [Pg.1173]    [Pg.119]    [Pg.324]    [Pg.101]    [Pg.298]    [Pg.444]   
See also in sourсe #XX -- [ Pg.59 , Pg.60 ]

See also in sourсe #XX -- [ Pg.59 , Pg.60 ]



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